feat(breakglass): add "back up a world now" console peer (§B4 Sync)

Adds a break-glass console operation that snapshots a stopped world by
calling the felis-api internal face while the API is alive, rather than
rendering the backup Job locally: the Job needs felis-api deployment
coordinates the console does not hold.

The peer resolves the felis-api-internal ClusterIP Service + service
token from the control namespace, POSTs the internal backup endpoint
with the operator os_user for audit attribution, and maps 409/503/404
to friendly outcome cards. Core decision logic lives in backupnow.go
(unit-tested against a fake client + httptest); tui_backupnow.go is the
untested bubbletea glue mirroring tui_halt.go.

docs/openapi.yaml

@@ -1034,6 +1034,18 @@ paths:
       security: [{ serviceToken: [] }]
       parameters:
         - { name: name, in: path, required: true, schema: { type: string } }
+      requestBody:
+        required: false
+        description: >-
+          Optional accountability hint. The console passes the OS user at the
+          keyboard so the audit row names the operator rather than the generic
+          "break-glass"; absent/blank falls back to "break-glass".
+        content:
+          application/json:
+            schema:
+              type: object
+              properties:
+                os_user: { type: string }
       responses:
         '202':
           description: Backup started.