feat: outbound webhooks — signed event delivery + delivery log

Every audited action now emits a "resource.action" event (bare actions
get resource-qualified; already-qualified actions like service.clone
pass through). Webhooks subscribe per-user with exact names, resource.*
wildcards, or *.

- schema: outbound_webhooks + webhook_deliveries (sqlc + goose)
- dispatcher: 4 workers, 512-queue, 3 attempts with backoff, 10s timeout;
  deliveries record status/http-code/body(4KiB)/duration
- signing: X-Containr-Signature sha256=<hmac> over raw body;
  X-Containr-Event + X-Containr-Delivery headers; custom headers per hook
- api: CRUD + /deliveries + /test (ping) under authed group
- fix: SetAuditDB never called — LogAudit was a silent no-op at every
  call site; now wired at boot
- coverage: service create/delete audited (previously uninstrumented)
- cli: containr webhooks list|create|update|delete|deliveries|test
- mcp: 6 tools, delete requires confirm
- frontend: /settings/webhooks page — list/create/expand-deliveries/
  test/disable/delete, secret-shown-once banner; nav + account menu
- openapi + regenerated types; CLI.md + docs snapshot; roadmap ticks

app/backend/sqlc/schema.sql

@@ -275,3 +275,30 @@ CREATE TABLE user_tokens (
     revoked_at TIMESTAMP WITH TIME ZONE,
     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
 );
+
+CREATE TABLE outbound_webhooks (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    name VARCHAR(255) NOT NULL,
+    url VARCHAR(500) NOT NULL,
+    secret TEXT NOT NULL DEFAULT '',
+    events JSONB NOT NULL DEFAULT '[]'::jsonb,
+    headers JSONB,
+    enabled BOOLEAN NOT NULL DEFAULT true,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+CREATE TABLE webhook_deliveries (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    webhook_id UUID NOT NULL REFERENCES outbound_webhooks(id) ON DELETE CASCADE,
+    event VARCHAR(255) NOT NULL,
+    payload JSONB,
+    status VARCHAR(50) NOT NULL DEFAULT 'pending',
+    response_status INTEGER,
+    response_body TEXT,
+    attempts INTEGER NOT NULL DEFAULT 0,
+    duration_ms INTEGER,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    delivered_at TIMESTAMP WITH TIME ZONE
+);