feat(hub)!: drop the catalog-blocks deploy mount (#784)

The hub mounts only stock routes plus Corbits libraries; the on-demand
catalog-block deploy route (POST /api/tenants/:tenantId/catalog-blocks/
:assetName/deploy) built workflow JSON from workflow packages and wrote
an asset directly from apps/hub, which is hub-local product logic the
owner ruling forbids.

Deletes apps/hub/src/catalog-blocks/* (module, routes, and their tests)
and the mount + its inline deployWorkflowSource/workflowDeployer wiring
in apps/hub/src/index.ts. The Available section's on-demand Add action
has no stock replacement yet, so it is removed along with the client's
deployCatalogBlock call; the section is read-only until a deploy path
lands on stock rails. The separate GET /workflows/available listing
(packages/workflows) is untouched.

Deleted tests:
- apps/hub/src/catalog-blocks/catalog-block-routes.test.ts
- apps/hub/src/catalog-blocks/catalog-blocks.test.ts
- apps/web/test/routines-available-section.test.tsx: "Add posts to the
  catalog-blocks deploy route and the entry disappears from Available"
  (route deleted); the disabled-Add-button assertions in the missing-
  connection test were folded into a read-only reason+link check.

Author: TheGreatAxios