merge: integrate main into experimental (preserve PBI-081 simplification)
Merge main's 93 commits into experimental, preserving architectural updates
decisions:
- Keep ResourceGovernor as centralized pool registry (experimental's PBI-081 Phase 2)
- Translate all PoolManager API calls to ResourceGovernor equivalents
- Remove PoolManager.{h,cpp} from build (absorbed into ResourceGovernor)
- Preserve main's enhancements: RepairService, IOCoordinator, GradientLimiter,
embed_preparer, GPU info, plugin trust, 60+ new test files
- Take main's version for 28 of 31 conflicts (more comprehensive rewrites)
- Keep experimental's ResourceGovernor.h (expanded pool API)
- Manual merge for .vscode/settings.json (use workspace-relative paths)
207532f46a