fix(orchestrator): prioritize real thread CWD in workspace selection and read renamed SQLite thread names

[openclawq]

Summary

This PR addresses two critical issues where sessions (specifically renamed sessions like /rename svmnew0910 or sessions under active workspaces like svmpy) fail to display properly in /use and /list target pickers:

1. SQLite Renamed Threads (threads.name) Support:

   • In modern Codex SQLite schemas, /rename updates the threads.name column while leaving threads.title as the initial long prompt summary.
   • internal/codexstate/sqlite_threads.go previously only queried title, resulting in renamed sessions retaining their old generated names.
   • Added schema column detection to select COALESCE(NULLIF(name, ''), title) AS title.

2. Managed Headless Pool Workspace Key Contamination Fix:

   • When preheating managed headless instances running in the background state directory (e.g., ~/.local/state/codex-remote), receiving an EventThreadsSnapshot previously overwrote unrelated thread records' WorkspaceKey to the headless instance's workspace root.
   • Downstream session filtering (threadBelongsToInstanceWorkspace and threadWorkspaceKeyFromRecord) previously prioritized thread.WorkspaceKey over thread.CWD, causing sessions located in workspaces like svmpy to be filtered out (0/50 matching) whenever their key was contaminated.
   • Fixed EventThreadsSnapshot to avoid contaminating thread workspace keys with unrelated instance roots.
   • Fixed threadBelongsToInstanceWorkspace and threadWorkspaceKeyFromRecord to prioritize the thread's real physical CWD and detect cross-workspace hierarchy mismatches.

Changes

• internal/codexstate/sqlite_threads.go:
  • Dynamically check for name column on threads table via PRAGMA table_info.
  • Fallback cleanly to title when name does not exist.
  • Added unit test TestSQLiteThreadCatalogPrefersRenamedNameColumn.
• internal/core/orchestrator/service.go:
  • Preserve thread's real CWD workspace mapping in EventThreadsSnapshot when !cwdBelongsToInstanceWorkspace(inst, thread.CWD).
• internal/core/orchestrator/service_surface_selection.go:
  • Prioritize thread.CWD over potentially contaminated WorkspaceKey in threadBelongsToInstanceWorkspace.
• internal/core/orchestrator/service_thread_global.go:
  • Reconcile threadWorkspaceKeyFromRecord against thread.CWD hierarchy.
• internal/core/orchestrator/service_target_picker_polluted_workspace_test.go:
  • Unit tests verifying target picker options inclusion and snapshot isolation.
• docs/implemented/headless-pool-workspace-thread-selection-fix.md & docs/README.md:
  • Full architecture analysis and lifecycle documentation.

Verification

• go test -v ./internal/codexstate -run TestSQLiteThreadCatalogPrefersRenamedNameColumn (PASS)
• go test -v ./internal/core/orchestrator -run "TestTargetPickerSessionOptionsIncludesThreadsWithCrossInstancePollutedWorkspaceKey|TestEventThreadsSnapshotDoesNotPolluteThreadWorkspaceKeyFromUnrelatedInstance" (PASS)
• bash scripts/check/pre-commit.sh (PASS)