feat: auto-revive in-review tasks with failed pre-merge workflow steps

Adds a SelfHealingManager scan that finds tasks parked in in-review with
a failed pre-merge workflow step and no active session, and sends them
back through the existing sendTaskBackForFix flow (PROMPT.md injection,
step reset, todo → in-progress). Bounded by a new maxPostReviewFixes
setting (default 1) and a per-task postReviewFixCount so a persistently-
failing verifier cannot ping-pong a task indefinitely.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/core/src/settings-schema.ts

@@ -103,6 +103,7 @@ export const DEFAULT_PROJECT_SETTINGS = {
   autoUnpauseBaseDelayMs: 300_000,
   autoUnpauseMaxDelayMs: 3_600_000,
   maxStuckKills: 6,
+  maxPostReviewFixes: 1,
   maxSpawnedAgentsPerParent: 5,
   maxSpawnedAgentsGlobal: 20,
   maintenanceIntervalMs: 900_000,