query: delete the caller-less CodeLexicalProjectionAdapterV1::new_published and share projection metadata by Arc

[ScriptedAlchemy]

Follow-up from #1045 (bf17a7c). After search-eval moved to one-pass scoped partitioning through new_admitted:

• CodeLexicalProjectionAdapterV1::new_published (in tracedecay-query) has no production caller; only crates/tracedecay-query/tests/search_quality_suite still uses it. Delete it and point the suite at new_admitted (or make new_published the single shared-source constructor and delete the other — one constructor, not two).
• CodeLexicalProjectionMetadataV1 is still cloned once per scope set because the adapter owns it by value. Let new_admitted take impl Into<Arc<…>> (metadata and the qualified-names map) so search-eval's per-scope adapters share one immutable copy.

Both must keep the packaged search-quality digests (WORKLOAD_SHA256, report_tests pins) unchanged. Prove with cargo test -p tracedecay-query --all-targets and cargo test -p tracedecay-search-eval --all-targets.

[ScriptedAlchemy]

Landed on the #707 branch at f1cc904 (lane fable/parse-1104-1102, 4dcd3aa).

new_published is deleted; the search-quality suite builds its generation-backed projection through new_admitted, which is now the single shared-source constructor. new_admitted / new / CodeLexicalProjectionBuildV1::new_admitted accept impl Into<Arc<…>> for both the projection metadata and the qualified-names map, and search-eval's build_query_projections passes one Arc of each to every scoped adapter instead of cloning the metadata and slicing the names per scope. WORKLOAD_SHA256 and the report_tests pins are unchanged; on the tip cargo test -p tracedecay-query -p tracedecay-search-eval --all-targets is 454 passed / 0 failed and workspace clippy -D warnings is clean.

Observed, not changed: new_admitted_with_deadline is private with one None caller, and CodeLexicalProjectionBuildV1::new_admitted is test-only.