docs(ri-050): forge fail-closed docs + TASKS status catch-up (#1275)

- README + skills/mosaic-forge/SKILL.md: bare 'mosaic forge run/resume'
  now documents the typed FORGE_NO_EXECUTOR fail-closed behavior and
  --simulate for explicit typed simulation (fast-follow to RI-2-001).
- docs/release-integrity/TASKS.md: rows catch up to measured reality -
  CI green at pinned heads (#1276 2475, #1277 2476, #1278 2477, #1293
  2465, #1294 2466), review evidence recorded, RI-2-001 prior-red root
  cause corrected (CI-agent contention, superseding fleet-test theory).

Stacks on docs/ri-050-mission-bootstrap (#1276) - merge after #1278.

skills/mosaic-forge/SKILL.md

@@ -133,10 +133,13 @@ When the full `@mosaicstack/forge` package is available, Forge uses MACP task ex
 
 ```bash
 # Run from CLI
-mosaic forge run path/to/brief.md
+# Fails closed with a typed FORGE_NO_EXECUTOR capability error when no real
+# executor is wired — pass --simulate to opt into explicit typed simulation
+# (every result carries status `simulated`, which satisfies nothing).
+mosaic forge run path/to/brief.md [--simulate]
 
-# Resume interrupted run
-mosaic forge resume .forge/runs/20260401-143022/
+# Resume interrupted run (same fail-closed rule as forge run)
+mosaic forge resume .forge/runs/20260401-143022/ [--simulate]
 
 # Check status
 mosaic forge status .forge/runs/20260401-143022/