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/migrations_goose/20261103000000_outbound_webhooks.sql

@@ -0,0 +1,36 @@
+-- +goose Up
+-- Outbound webhooks: user-owned HTTP endpoints that receive signed
+-- platform events (resource.action), with a delivery log.
+CREATE TABLE IF NOT EXISTS 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 timestamptz DEFAULT now(),
+    updated_at timestamptz DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS 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 timestamptz DEFAULT now(),
+    delivered_at timestamptz
+);
+
+CREATE INDEX IF NOT EXISTS idx_outbound_webhooks_user ON outbound_webhooks(user_id);
+CREATE INDEX IF NOT EXISTS idx_webhook_deliveries_webhook ON webhook_deliveries(webhook_id, created_at DESC);
+
+-- +goose Down
+DROP TABLE IF EXISTS webhook_deliveries;
+DROP TABLE IF EXISTS outbound_webhooks;