refactor: extract sessions page components (Task 4.2)

- Extract CreateSessionForm component with self-contained form state
- Extract SessionList component managing confirmations and health polling
- Extract SessionCard presentational component for active/recent variants
- Add ConfirmDialog reusable UI primitive
- Slim sessions page from ~668 lines to 156 lines
- Keep lastSession section inline per design decision

Quality gates: tsc (pass), eslint (pass), build (pass)
Refs: repo-restructure Task 4.2

progress.md

@@ -1,10 +1,36 @@
 # Progress
 
 ## Status
-In Progress
+In Progress — Task 4.2 completed
 
 ## Tasks
+- [x] 1.1 Centralize types and extract seed data
+- [x] 1.2 Extract FileBrowser and shared UI primitives
+- [x] 2.1 Extract global styles and tokens
+- [x] 2.2 Extract CSS modules (terminal + git)
+- [x] 2.3 Extract CSS modules (session/settings) + delete styles.css
+- [x] 3.1 Extract shared auth dependencies
+- [x] 3.2 Create Pydantic schemas directory
+- [x] 3.3 Split services/docker.py
+- [x] 3.4 Slim tool_instances router
+- [x] 3.5 Slim git_repositories and config_profiles routers
+- [x] 4.1 Split tool-workshop page into tabs
+- [x] 4.2 Extract sessions page components
+- [ ] 4.3 Extract dashboard and repo-workspace components
+- [ ] 4.4 Rename files to naming convention
+- [ ] 5.1 Add tests for extracted components
+- [ ] 5.2 Documentation and cleanup
 
-## Files Changed
+## Files Changed (Task 4.2)
+- NEW: components/ui/ConfirmDialog.tsx
+- NEW: components/features/session/SessionCard.tsx
+- NEW: components/features/session/SessionList.tsx
+- NEW: components/features/session/CreateSessionForm.tsx
+- NEW: components/features/session/index.ts
+- MOD: pages/sessions.tsx (668 → 156 lines)
+- MOD: components/ui/index.ts
 
 ## Notes
+- Sessions page slimmed from 668 to 156 lines
+- All quality gates pass: typecheck, lint, build
+- No behavior changes