docs(meta): record M1 in-game test results — all passing

Human-tested: provinces show correct culture/religion, decision menu
clean, character sheet correct, 5-year playthrough with no crashes.
305 mod-related log entries are all expected (303 vanilla cascade,
2 unused variables).

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

docs/milestones/M1-foundation.md

@@ -490,7 +490,7 @@ display errors in-game.
 | 1.2 Culture Pillars | PASS | All pillars have `type`, `is_shown`, `color`; `head_determination` added to all cultures |
 | 1.3 Scripted Triggers | PASS | `is_feruchemist_trigger` matches only active; `has_allomantic_potential_trigger` excludes active allomancers; `has_any_*` variants exist |
 | 1.4 Unified Attention | PASS | Variable-based system (0-100) with tiered modifiers; zero references to `lord_ruler_attention_modifier` |
-| 1.5 Vanilla Suppression | PASS | 34 vanilla decision files suppressed; only Mistborn decisions remain |
+| 1.5 Vanilla Suppression | PASS | `replace_path` for `common/decisions` + 12 DLC subdirs; only Mistborn decisions remain |
 | 1.6 Game Rules | PASS | `mistborn_game_mode` with narrative/sandbox; mode triggers integrated |
 | 1.7 Localization Coverage | PASS | All 47 modifiers, game rules, opinion modifiers localized |
 
@@ -517,9 +517,23 @@ Remaining 335 warnings are all expected/deferred:
 - 30 missing-item: auto-generated MaA modifier formats (26) + dynasty CoAs (4)
 - 15 missing-file: art assets not yet generated
 
-### In-Game Testing
+### In-Game Testing (2026-02-08)
 
-Requires human player — see Testing Checkpoints above. Not yet performed.
+Tested by human player: launch, start as Devinshae Venture, 5-year playthrough.
+
+| Checkpoint | Result | Notes |
+|------------|--------|-------|
+| Province culture/religion | PASS | Luthadel shows Noble Scadrian / Steel Ministry (fixed via `replace_path="history/provinces"`) |
+| Decision menu | PASS | Only Mistborn decisions visible (fixed via `replace_path` for all decision dirs) |
+| Character sheet | PASS | Venture shows Noble Scadrian culture, Ministry faith, traits visible |
+| 5-year playthrough | PASS | No crashes, no visible errors, no vanilla bleed-through |
+
+**error.log analysis (305 mod-related entries):**
+- 303 vanilla `game_start.txt` cascade errors (vanilla special building effects on non-existent provinces — expected in TC)
+- 2 unused variable warnings (`mistborn_revealed_at_ball` — will be used in M7)
+- 0 duplicate localization keys
+- 0 missing localization keys
+- 0 crashes
 
 ## Risks & Mitigations