refactor(configuration): own the TraceDecay config model

[ScriptedAlchemy]

Moves the full TraceDecay configuration model and its loading, saving, validation, and path rules into tracedecay-configuration. Root, CLI, and dashboard callers import the owning implementation directly. Project adoption now lives in tracedecay-application.

The merged maintenance owner also consumes configuration. To avoid a dependency cycle, the shared CompactionThresholdConfig data type lives in the existing contracts crate; its serialized shape and defaults are unchanged. All consumers use that single definition, with no compatibility alias.

Validation on the corrected #707 integration: 36 configuration model tests, 10 compaction tests, 13 runtime configuration tests, and 6 moved-project adoption tests passed. Strict Clippy passed for six affected crates and again for root library/tests after integrating #1179 at 5485bc76f. Formatting and independent review passed. These checks do not claim full native runtime qualification.

Child of #707; addresses the configuration ownership portion of #1073.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-09T19:47:40.208701Z	f6f8d01	PR opened

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[github-actions]

Performance Comparison codex/tracedecay-total-redesign-plan-reopened → grok/w2-config-split

Total Elapsed Time: 4.35s → 4.10s (-5.7%)
CPU Baseline: 79.24µs → 88.27µs (+11.4%)
Benchmark ID: index-bench-timing

timing - Execution duration of functions.

+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| Function                                 | Calls                      | Avg                            | P95                             | Total                            | % Total                      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| tracedecay-index-bench                   | 1 → 1 (+0.0%)              | 4.35s → 4.10s (-5.7%)          | 4.35s → 4.10s (-5.7%)           | 4.35s → 4.10s (-5.7%)            | 100.00% → 100.00% (+0.0%)    |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.append_pages              | 13 → 13 (+0.0%)            | 134.26ms → 124.74ms (-7.1%)    | 189.01ms → 169.74ms (-10.2%)    | 1.75s → 1.62s (-7.4%)            | 40.16% → 39.57% (-1.5%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.workers.install               | 83 → 83 (+0.0%)            | 17.60ms → 14.41ms (-18.1%)     | 63.70ms → 48.10ms (-24.5%) 🚀   | 1.46s → 1.20s (-17.8%)           | 33.61% → 29.19% (-13.2%)     |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| domain.canonical.sha256                  | 110414 → 110414 (+0.0%)    | 10.05µs → 9.51µs (-5.4%)       | 12.55µs → 12.85µs (+2.4%)       | 1.11s → 1.05s (-5.4%)            | 25.53% → 25.63% (+0.4%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.build.and_publish             | 2 → 2 (+0.0%)              | 495.10ms → 476.74ms (-3.7%)    | 538.97ms → 555.75ms (+3.1%)     | 990.20ms → 953.48ms (-3.7%)      | 22.78% → 23.27% (+2.2%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.batch.sqlite              | 13 → 13 (+0.0%)            | 69.61ms → 71.52ms (+2.7%)      | 91.88ms → 96.60ms (+5.1%)       | 904.91ms → 929.76ms (+2.7%)      | 20.82% → 22.69% (+9.0%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.batch.postings            | 13 → 13 (+0.0%)            | 60.90ms → 62.45ms (+2.5%)      | 82.05ms → 85.52ms (+4.2%)       | 791.73ms → 811.89ms (+2.5%)      | 18.22% → 19.81% (+8.7%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.finalization.advance_wake | 14 → 14 (+0.0%)            | 46.86ms → 45.74ms (-2.4%)      | 287.05ms → 285.74ms (-0.5%)     | 656.04ms → 640.36ms (-2.4%)      | 15.09% → 15.63% (+3.6%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.chunk.index_file              | 276 → 276 (+0.0%)          | 2.24ms → 2.29ms (+2.2%)        | 3.31ms → 3.35ms (+1.2%)         | 619.53ms → 630.71ms (+1.8%)      | 14.25% → 15.39% (+8.0%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.extract.parser_artifact       | 276 → 276 (+0.0%)          | 2.06ms → 2.15ms (+4.4%)        | 3.10ms → 3.28ms (+5.8%)         | 567.33ms → 592.55ms (+4.4%)      | 13.05% → 14.46% (+10.8%)     |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.prepare_pages             | 13 → 13 (+0.0%)            | 55.48ms → 43.69ms (-21.3%) 🚀  | 84.87ms → 62.78ms (-26.0%) 🚀   | 721.21ms → 568.00ms (-21.2%) 🚀  | 16.59% → 13.86% (-16.5%)     |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.batch.postings.ngram_rows | 13 → 13 (+0.0%)            | 34.27ms → 34.95ms (+2.0%)      | 46.83ms → 47.55ms (+1.5%)       | 445.54ms → 454.36ms (+2.0%)      | 10.25% → 11.09% (+8.2%)      |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| query.artifact.batch.parallel_prepare    | 13 → 13 (+0.0%)            | 45.51ms → 34.47ms (-24.3%) 🚀  | 66.62ms → 49.51ms (-25.7%) 🚀   | 591.60ms → 448.05ms (-24.3%) 🚀  | 13.61% → 10.93% (-19.7%)     |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.build.assemble                | 2 → 2 (+0.0%)              | 215.84ms → 211.97ms (-1.8%)    | 227.80ms → 219.68ms (-3.6%)     | 431.68ms → 423.94ms (-1.8%)      | 9.93% → 10.35% (+4.2%)       |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+
| code_index.chunk.build                   | 276 → 276 (+0.0%)          | 1.41ms → 1.42ms (+0.7%)        | 2.03ms → 2.06ms (+1.5%)         | 388.25ms → 392.58ms (+1.1%)      | 8.93% → 9.58% (+7.3%)        |
+------------------------------------------+----------------------------+--------------------------------+---------------------------------+----------------------------------+------------------------------+

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