fix: improve note interactions and markdown LaTeX support

## Bug Fixes

### Note Card Actions
- Fix broken size change functionality (missing state declaration)
- Implement React 19 useOptimistic for instant UI feedback
- Add startTransition for non-blocking updates
- Ensure smooth animations without page refresh
- All note actions now work: pin, archive, color, size, checklist

### Markdown LaTeX Rendering
- Add remark-math and rehype-katex plugins
- Support inline equations with dollar sign syntax
- Support block equations with double dollar sign syntax
- Import KaTeX CSS for proper styling
- Equations now render correctly instead of showing raw LaTeX

## Technical Details

- Replace undefined currentNote references with optimistic state
- Add optimistic updates before server actions for instant feedback
- Use router.refresh() in transitions for smart cache invalidation
- Install remark-math, rehype-katex, and katex packages

## Testing

- Build passes successfully with no TypeScript errors
- Dev server hot-reloads changes correctly

_bmad-output/planning-artifacts/bmm-workflow-status.yaml

@@ -0,0 +1,43 @@
+# Workflow Status Template
+
+# This tracks progress through BMM methodology Analysis, Planning, and Solutioning phases.
+# Implementation phase is tracked separately in sprint-status.yaml
+
+# STATUS DEFINITIONS:
+# ==================
+# Initial Status (before completion):
+#   - required: Must be completed to progress
+#   - optional: Can be completed but not required
+#   - recommended: Strongly suggested but not required
+#   - conditional: Required only if certain conditions met (e.g., if_has_ui)
+#
+# Completion Status:
+#   - {file-path}: File created/found (e.g., "docs/product-brief.md")
+#   - skipped: Optional/conditional workflow that was skipped
+
+generated: "2026-01-09"
+project: "Memento"
+project_type: "intermediate"
+selected_track: "bmad-method"
+field_type: "brownfield"
+workflow_path: "_bmad/bmm/workflows/workflow-status/paths/method-brownfield.yaml"
+workflow_status:
+  # Phase 0: Documentation (Prerequisite for brownfield)
+  document-project: docs/index.md
+
+  # Phase 1: Analysis (Optional)
+  brainstorm-project: optional
+  research: optional
+
+  # Phase 2: Planning
+  prd: _bmad-output/planning-artifacts/prd.md
+  create-ux-design: conditional
+
+  # Phase 3: Solutioning
+  create-architecture: required
+  create-epics-and-stories: _bmad-output/planning-artifacts/epics.md
+  test-design: optional
+  implementation-readiness: _bmad-output/planning-artifacts/implementation-readiness-report-2026-01-09.md
+
+  # Phase 4: Implementation
+  sprint-planning: required