Reliable local package discovery and shared source reuse

Xcode package discovery now follows explicit local package dependency paths before searching the workspace. Duplicate products or conflicting package identities report both candidate paths and explain how to select the intended dependency, instead of silently choosing a stale copy.

Remote Swift packages reuse a shared Git repository across worktrees while keeping their source checkout workspace-local. Pinned commits remain available to other worktrees, and failed acquisitions do not publish partial checkouts. Servers that reject shallow fetches still work through an ordinary-fetch fallback.

Warm graph loads reuse successful manifest dumps for referenced packages. Manifest edits, source changes, added or removed package files, tool changes and environment changes invalidate the saved metadata.