docs(05-02): record plan close-out in STATE and ROADMAP

- Advance to plan 3 of 6 and mark DATA-04/05/07/09 complete

.planning/STATE.md

@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 05-01-PLAN.md
-last_updated: "2026-09-18T16:50:24.472Z"
+stopped_at: Completed 05-02-PLAN.md
+last_updated: "2026-09-18T17:24:46.649Z"
 last_activity: 2026-09-18
 progress:
   total_phases: 15
   completed_phases: 4
   total_plans: 23
-  completed_plans: 18
-  percent: 78
+  completed_plans: 19
+  percent: 83
 ---
 
 # Project State
@@ -26,11 +26,11 @@ See: .planning/PROJECT.md (updated 2026-09-16)
 ## Current Position
 
 Phase: 05 (data-layer-full-fidelity) — EXECUTING
-Plan: 2 of 6
+Plan: 3 of 6
 Status: Ready to execute
 Last activity: 2026-09-18
 
-Progress: [████████░░] 78%
+Progress: [████████░░] 83%
 
 ## Performance Metrics
 
@@ -64,6 +64,7 @@ Progress: [████████░░] 78%
 | Phase 04 P04-03 | 6 min | 3 tasks | 15 files |
 | Phase 04 P04-04 | 8 min | 3 tasks | 9 files |
 | Phase 05 P01 | 16 min | 4 tasks | 37 files |
+| Phase 05 P02 | 27 min | 3 tasks | 32 files |
 
 ## Accumulated Context
 
@@ -124,6 +125,11 @@ Recent decisions affecting current work:
 - [Phase 05]: Lifecycle Has* interfaces use GORM-native signatures; WithSoftDeleteCascade does not open a new transaction — DATA-03 primitive
 - [Phase 05]: Paginate coerces nil data to []; RegisterJoinTable fails loud on nil db — DATA-10 and pivot-write contract
 - [Phase 05]: DATA-09 migration count is not an acceptance number (D-01); HTTP DTO fuzz moves to Phase 12 (D-07)
+- [Phase 05]: Jsonable payload field is Data, not Value, because driver.Valuer.Value() collides under go vet — go vet rejects a field and method both named Value; type Jsonable[T] T is illegal
+- [Phase 05]: KeepMarketPriceSource is a gorm-ignored Album flag set by SaveAlbum when requested contains market_price_source — GORM has no Eloquent isDirty; the flag preserves stampMarketPrice source provenance
+- [Phase 05]: CollectionFillFields is name+description; PHP has no CollectionWriteService — D-05 service list is a subset of Fillable excluding owner_id
+- [Phase 05]: Various Artists natural key is name_key='various artists' (PHP seed), slug various-artists — seed_genre_and_various_artist_taxonomy.php uses a spaced name_key
+- [Phase 05]: go-playground/validator v10.30.4 is the STACK-named rule engine behind lagoon.Validate — STACK.md already named this library; lagoon.Validate translates Laravel rule strings onto Var()
 
 ### Pending Todos
 
@@ -145,6 +151,6 @@ Items acknowledged and carried forward from previous milestone close:
 
 ## Session Continuity
 
-Last session: 2026-09-18T16:50:24.446Z
-Stopped at: Completed 05-01-PLAN.md
+Last session: 2026-09-18T17:24:44.978Z
+Stopped at: Completed 05-02-PLAN.md
 Resume file: None