feat: implement tool-session progress panel and live list updates

- Add SessionOperationsContext + SessionProgressPanel for global,
  non-blocking lifecycle progress (create/start/stop/restart/delete/
  recreate-tunnel) driven by SSE events.
- Promote SessionsContext to authoritative shared session state with
  refresh, addOrUpdateSession, and removeSession helpers.
- Wire AppShell, DashboardPage, SessionsPage, useInstanceActions,
  ToolStarter, and InstanceList into shared state so lists update
  immediately after create/delete without manual refresh.
- Remove legacy blocking overlays from CreateSessionForm, SessionCard,
  and InstanceList; keep disabled states and inline spinners only.
- Update DashboardPage tests to wrap with SessionsProvider and
  SessionOperationsProvider.
- Add .cache/ to .gitignore.

Quality gates: npm run typecheck, npm run lint, npm test -- --run
(82 passed).

openspec/changes/tool-session-progress-and-updates/.pi-map.index.md

@@ -0,0 +1,37 @@
+# . (index)
+dir: .
+
+## Project Map Protocol
+
+1. Read this protocol and the root `.pi-map.index.md` first.
+2. Use `index:` / `map:` references to open relevant directory indexes and maps.
+3. Load indexes before rich maps during task-start navigation.
+4. Read the local rich map and actual source before editing.
+5. Treat non-empty `## dirty` sections in either artifact as stale.
+6. If source and generated artifacts disagree, trust source.
+7. If map and index disagree, trust neither blindly; verify from source and regenerate the pair.
+8. After editing source, run `project_map_patch` for each changed file.
+9. Before broad architectural claims or final handoff, run `project_map_validate` when freshness matters.
+
+Trust boundary: index routes, map orients, source decides.
+
+## role
+Frontend architecture specification for real-time session progress tracking using Server-Sent Events and shared React state management.
+## parent
+-
+## children
+- specs
+  index: specs/.pi-map.index.md
+  map: specs/.pi-map.md
+## files
+- .openspec.yaml
+- design.md
+- proposal.md
+- tasks.md
+## links
+index: ./.pi-map.index.md
+map: ./.pi-map.md
+## workflows
+-
+## dirty
+-