docs(03): create phase plan

Phase 03: Component System
- 2 plan(s) in 2 wave(s)
- Wave 1: 03-01 (registration and lifecycle) - parallel
- Wave 2: 03-02 (HTMX routing and response) - sequential
- Ready for execution

.planning/ROADMAP.md

@@ -68,11 +68,11 @@ Plans:
   2. Component lifecycle (init, onRun) executes correctly per request
   3. Components can define HTMX handlers that respond to data-attribute triggers
   4. HTMX handlers return HTML fragments that swap into the page
-**Plans**: TBD
+**Plans**: 2 plans
 
 Plans:
-- [ ] 03-01: Component registration and lifecycle
-- [ ] 03-02: HTMX handler routing and response
+- [ ] 03-01-PLAN.md - Component registration and lifecycle (SummerComponent trait, YAML property schemas, ComponentManager)
+- [ ] 03-02-PLAN.md - HTMX handler routing and response (HtmxResponse, Pebble templates, ComponentRoutes, CSRF)
 
 ### Phase 4: Theme Engine
 **Goal**: Render themes with layouts, partials, and Vue integration
@@ -208,7 +208,7 @@ Phases execute in numeric order: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10
 |-------|----------------|--------|-----------|
 | 1. Foundation | 3/3 | Complete | 2026-02-05 |
 | 2. Plugin System | 0/3 | Planned | - |
-| 3. Component System | 0/2 | Not started | - |
+| 3. Component System | 0/2 | Planned | - |
 | 4. Theme Engine | 0/2 | Not started | - |
 | 5. CLI Scaffolding | 0/2 | Not started | - |
 | 6. Backend Authentication | 0/3 | Not started | - |