chore(workspace): remove redundant nested lockfiles + workspace.yaml

Three pnpm artifacts that were either Pre-Consolidation leftovers or
unintentional drift:

  - apps/context/pnpm-lock.yaml + apps/context/pnpm-workspace.yaml
    apps/context used to be its own nested workspace declaring
    apps/* and packages/*. After consolidation only apps/context/
    apps/mobile remains, and the root pnpm-workspace.yaml already
    matches it via 'apps/*/apps/*'. The nested lockfile (242 KB)
    was a separate dependency graph drifting independently from
    the root.

  - services/mana-media/packages/client/pnpm-lock.yaml
    Anomalous lockfile in a workspace sub-package. The root
    workspace already covers services/*/packages/* — no reason
    for client/ to maintain its own resolution.

Verified after deletion:
  - pnpm install completes cleanly (~16s) and now resolves
    apps/context/apps/mobile from the root lockfile (pnpm list
    confirms the workspace registration)
  - apps/api type-check still 0 errors
  - mana-auth tests still 19/19 passing

Tracked as item #26 in docs/REFACTORING_AUDIT_2026_04.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/context/pnpm-workspace.yaml

@@ -1,3 +0,0 @@
-packages:
-  - "apps/*"
-  - "packages/*"