docs(04-01): complete BaseProcessor and ParseProcessor plan

- BaseProcessor abstract class with unified interface
- ParseProcessor wrapping LinkParser for URL parsing
- ParseInput/ParseOutput schemas for parse step
- All tests passing (18 tests)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/STATE.md

@@ -4,14 +4,14 @@ milestone: v1.0
 milestone_name: milestone
 current_plan: 3
 status: executing
-stopped_at: Phase 4 context gathered
-last_updated: "2026-03-13T14:37:52.597Z"
+stopped_at: Completed 04-analysis-orchestration-04-01-PLAN.md
+last_updated: "2026-03-13T15:15:58.972Z"
 last_activity: 2026-03-13
 progress:
   total_phases: 4
   completed_phases: 3
-  total_plans: 7
-  completed_plans: 7
+  total_plans: 12
+  completed_plans: 8
   percent: 8
 ---
 
@@ -60,6 +60,7 @@ Progress: [█░░░░░░░░░] 8%
 | Phase 02-platform-skills P01 | 5 | 3 tasks | 5 files |
 | Phase 02-platform-skills P03 | 7min | 3 tasks | 4 files |
 | Phase 02 P02 | 8 | 4 tasks | 7 files |
+| Phase 04-analysis-orchestration P01 | 5min | 3 tasks | 6 files |
 
 ## Accumulated Context
 
@@ -84,6 +85,8 @@ Recent decisions affecting current work:
 - [Phase 02]: State recording only after all retries exhausted (not on each retry attempt)
 - [Phase 02]: Video content returns empty string (handled by ASR in Phase 3)
 - [Phase 02]: Article content fetching as placeholder (requires additional API implementation)
+- [Phase 04-01]: BaseProcessor uses ABC with @abstractmethod for process() method
+- [Phase 04-01]: ParseInput content_id and platform default to empty string (populated after parse)
 
 ### Pending Todos
 
@@ -99,6 +102,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-13T14:37:52.596Z
-Stopped at: Phase 4 context gathered
-Resume file: .planning/phases/04-analysis-orchestration/04-CONTEXT.md
+Last session: 2026-03-13T15:15:58.970Z
+Stopped at: Completed 04-analysis-orchestration-04-01-PLAN.md
+Resume file: None