docs(12-04): complete Plan & Task tRPC procedures plan

Tasks completed: 3/3
- Add PlanRepository to tRPC context
- Add Plan tRPC procedures (CRUD)
- Add createTasksFromDecomposition procedure

SUMMARY: .planning/phases/12-phase-task-decomposition/12-04-SUMMARY.md

.planning/STATE.md

@@ -10,11 +10,11 @@ See: .planning/PROJECT.md (updated 2026-01-31)
 ## Current Position
 
 Phase: 12 of 13 (Phase Task Decomposition)
-Plan: 3 of 8 in current phase
+Plan: 4 of 8 in current phase
 Status: In progress
-Last activity: 2026-02-01 — Completed 12-03-PLAN.md
+Last activity: 2026-02-01 — Completed 12-04-PLAN.md
 
-Progress: ██████░░░░ 59%
+Progress: ██████░░░░ 61%
 
 ## Performance Metrics
 
@@ -150,6 +150,8 @@ Recent decisions affecting current work:
 - 12-02: getNextNumber uses max() aggregate, returning 1 if no plans exist (same pattern as PhaseRepository)
 - 12-03: Task execution order adjusted - Task 3 first since Tasks 1-2 depend on AgentStoppedEvent reason type
 - 12-03: handleDecomposeOutput follows exact structure of handleBreakdownOutput for pattern consistency
+- 12-04: Extended TaskRepository with createDependency for hexagonal architecture compliance
+- 12-04: createTasksFromDecomposition maps task numbers to IDs for dependency creation
 
 ### Pending Todos
 
@@ -170,5 +172,5 @@ None.
 ## Session Continuity
 
 Last session: 2026-02-01
-Stopped at: Completed 12-03-PLAN.md (Agent Manager Decompose Mode)
+Stopped at: Completed 12-04-PLAN.md (Plan & Task tRPC Procedures)
 Resume file: None