refactor: retire src/utils through owner-specific deletion slices

[thymikee]

Outcome

Retire src/utils through owner-specific deletion slices. This is an umbrella: do not submit one giant move PR. First re-audit current main, publish concrete child issues for each independently reviewable owner slice, then execute only a child issue.

Required child slices

1. Snapshot presentation policy to cohesive src/snapshot/ submodules.
2. Host/file/process mechanics through existing host-kit capabilities while retaining app-log, provisioning, transport, update, Swift, and video policy with exact domain owners.
3. Command/core parsing and validation beside their owning command/runtime modules.
4. Client/CLI/MCP presentation beside the surface that owns each output.
5. Proven multi-owner pure primitives into existing package facets only when closure improves.
6. Terminal deletion of src/utils, stale zone metadata, and a planted-red no-regrowth rule.

Each child must name every source file, exact destination, production importers, focused tests, and blockers. Ambiguous files such as app-log-files.ts, swift-cache.ts, video*.ts, runtime-transport.ts, output.ts, screenshot-result.ts, and timing-safe-equal.ts must not be assigned by filename or Node-builtin heuristics.

Constraints

• Preserve behavior, output text, wire shape, error codes, timeout/retry semantics, and lazy closure.
• No utils, common, or shared replacement package/directory.
• No compatibility shims or internal barrels.
• Tests move with sources; splits require characterization before changing boundaries.
• Prefer deletion and consolidation. Across the program, production LOC should decrease; every child PR reports gross additions/deletions and explains unavoidable growth.
• Before pushing each child: pnpm format and pnpm check:affected --run.

Done criteria

• Every tracked src/utils file has exactly one accepted owner and child issue.
• Child issues carry explicit Blocked by: relationships.
• The final child proves git ls-files 'src/utils/**' is empty and the no-regrowth plant fails by name.