feat: add admin/internal database API with CRUD, read-only query, and natural-language SQL endpoints

Add a new `/dbapi` router package providing a generic database API over `dataset`, restricted to admin sessions, admin API keys, and the internal gateway key. Includes:

- `tables.py`: list all tables and inspect table schemas
- `crud.py`: full CRUD operations (GET, POST, PATCH, DELETE) with soft-delete awareness, born-live inserts, `?include_deleted`, `.../restore`, and `?hard=true` purge
- `query.py`: validated read-only SELECT execution via sqlglot parsing, classification, and EXPLAIN dry-run; async query jobs with WebSocket streaming via `DbApiJobService`
- `nl.py`: natural-language-to-SQL conversion using the platform AI gateway with re-prompting until validation passes

Also register `DbApiJobService` and `PubSubService` in the service manager, add `DBAPI_DIR` to config data paths, and force cleartext `http://` connections to HTTP/1.1 in `curl_transport` to fix large request failures against uvicorn's HTTP/1.1-only internal gateway.

devplacepy/routers/docs/pages.py

@@ -468,6 +468,20 @@ DOCS_PAGES = [
         "admin": True,
         "section": SECTION_SERVICES,
     },
+    {
+        "slug": "services-dbapi",
+        "title": "Database API service",
+        "kind": "prose",
+        "admin": True,
+        "section": SECTION_SERVICES,
+    },
+    {
+        "slug": "services-pubsub",
+        "title": "Pub/Sub service",
+        "kind": "prose",
+        "admin": True,
+        "section": SECTION_SERVICES,
+    },
     # Architecture - platform design, structure, and development process (admins only)
     {
         "slug": "architecture",