Add heartbeat integration, planning phase, and auto-repair

- Add HeartbeatConfig for proactive periodic execution with channel notifications
- Add use_planning option to Worker for ActionPlan generation before tool execution
- Implement tool failure tracking in database (V3 migration)
- Add auto-repair via Builder for broken WASM tools in self_repair.rs
- Record tool failures in Worker for self-repair tracking
- Update .env.example with new configuration options

Co-Authored-By: Claude Opus 4.5 <[email protected]>

migrations/V3__tool_failures.sql

@@ -0,0 +1,20 @@
+-- Track tool execution failures for self-repair
+-- Tools that fail repeatedly can be automatically repaired by the builder
+
+CREATE TABLE IF NOT EXISTS tool_failures (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tool_name VARCHAR(255) NOT NULL,
+    error_message TEXT,
+    error_count INTEGER DEFAULT 1,
+    first_failure TIMESTAMPTZ DEFAULT NOW(),
+    last_failure TIMESTAMPTZ DEFAULT NOW(),
+    -- Store BuildResult for repair context
+    last_build_result JSONB,
+    repaired_at TIMESTAMPTZ,
+    repair_attempts INTEGER DEFAULT 0,
+    UNIQUE(tool_name)
+);
+
+CREATE INDEX idx_tool_failures_name ON tool_failures(tool_name);
+CREATE INDEX idx_tool_failures_count ON tool_failures(error_count DESC);
+CREATE INDEX idx_tool_failures_unrepaired ON tool_failures(tool_name) WHERE repaired_at IS NULL;