chore(desktop): delete dead persona catalog UI cluster (#2886)

## Summary

- Deletes 6 orphaned files in `desktop/src/features/agents/ui/` (556
lines) that formed a closed cluster with zero imports from the reachable
module graph — orphaned by the 1B dialog consolidation
(`PersonaCatalogSurface`, `PersonaCatalogSection`,
`PersonaCatalogDetailsSheet`, `PersonaCatalogSelectionBadge`,
`PersonaIdentity`, `PersonaLibraryEntryPoints`).
- Removes a stale `check-file-sizes.mjs` override entry for the
no-longer-existent `PersonaDialog.tsx`.

Verified dead two ways: import-graph reachability walk from all entry
points puts all six outside the reachable set, and `tsc --noEmit` passes
clean after deletion. Their `data-testid`s have zero references outside
the cluster. `PersonaCatalogDialog.tsx` is alive (`AgentsView` imports
it) and stays.

Independent of #1968 — pure dead code removal, no behavioral change.

desktop/scripts/check-file-sizes.mjs

@@ -219,20 +219,6 @@ const overrides = new Map([
   // (+3) — the new team-id spawn link and the runtime-layered instructions
   // field.
   ["src/shared/api/types.ts", 1047],
-  // readiness-gate: PersonaDialog.tsx threads computeLocalModeGate +
-  // requiredCredentialEnvKeys + RequiredFieldLabel so the "New agent" dialog
-  // shows required markers and credential amber rows (parity with
-  // CreateAgentDialog). +23 lines of gate wiring. Queued to split.
-  // config-bridge-aware requirements: useRuntimeFileConfigQuery wiring adds
-  // ~16 lines. Queued to split.
-  // baked-env-required-badge: useBakedBuildEnvKeysQuery + bakedEnvKeys wiring
-  // + correct exclusion-semantics for requiredEnvKeys adds ~14 lines.
-  // +2 lines: filter managed provider key from requiredEnvKeys (suppress dead-input locked row).
-  // global-agent-config parity: wire useGlobalAgentConfig into PersonaDialog
-  // (Gap A: global-aware computeLocalModeGate + drop bare requiredCredentialEnvKeys;
-  // Gap B: hasAutoOpenedAdvancedRef auto-expand effect) + effective-provider
-  // save gate + Inherit/Select-a-provider label. Queued to split.
-  ["src/features/agents/ui/PersonaDialog.tsx", 1080],
   // harness-persona-sync feature growth, queued to split in the resolver-unify
   // refactor followup. discovery.rs is dominated by the new test module
   // (the effective_agent_command / divergent / create-time override matrix);