refactor(qa-lab): localize orchestration declarations - #102005

What Problem This Solves

Seven QA Lab orchestration declarations were exported even though they have no repository consumers and are not part of the package's explicit public API.

Why This Change Was Made

Keep these declarations local to their owning modules while preserving the exported functions and result types that form the actual QA Lab surface. QaModelSelection was deliberately left exported because model-selection.ts is re-exported through a wildcard barrel.

User Impact

None. This is export-surface cleanup only; runtime behavior and supported QA Lab APIs are unchanged.

Evidence

• Fresh codebase-memory graph: 281,363 nodes / 1,134,383 edges.
• MCP graph search and repository-wide exact search found no external consumers or explicit barrel exports for the seven localized declarations.
• Testbox tbx_01kwzvzf75590qyxg6nkfwcdm2: post-rebase pnpm check:changed passed, including core and extension type/lint lanes.
• Seven focused patched suites passed: 70/70 tests.
• Full build passed after rebasing onto current origin/main.
• A wider eight-suite run was 70/71 because ci-smoke-plan.test.ts expects 89 scenarios while current main produces 98; the identical failure was reproduced on pristine current main.
• Fresh autoreview: local 0.89, pre-rebase branch 0.87, post-rebase branch 0.91; no accepted/actionable findings.