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/services/containers/files/bot.py

@@ -2537,13 +2537,14 @@ async def handle_mentions(dp: DevPlace, answered: set[str]) -> None:
                 reply = await _agent_answer_for_devplace(
                     f"You were @-mentioned in a DevPlace post. The message to you is:\n\n{message}\n\n"
                     f"Do what it asks, then answer it directly. Your reply is posted verbatim as a "
-                    f"comment, so write it as botje talking to the user — not as a report about what you did.",
+                    f"comment, so write it as botje talking to the user — not as a report about what you did. "
+                    f"Keep the entire reply within 1000 characters (the comment length limit).",
                     context=f"Post URL: {DEVPLACE_URL}/posts/{slug}",
                 )
 
                 dp.call(
                     "comments.create",
-                    content=reply[:5000],
+                    content=reply.strip()[:1000],
                     target_uid=post_uid,
                     target_type="post",
                 )
@@ -2597,10 +2598,13 @@ async def handle_dms(dp: DevPlace, answered: set[str]) -> None:
         try:
             reply = await _agent_answer_for_devplace(
                 content,
-                context=f"The user @{other_name} (uid {other_uid}) sent you a direct message.",
+                context=(
+                    f"The user @{other_name} (uid {other_uid}) sent you a direct message. "
+                    f"Keep the entire reply within 2000 characters (the message length limit)."
+                ),
             )
 
-            dp.call("messages.send", content=reply[:5000], receiver_uid=other_uid)
+            dp.call("messages.send", content=reply.strip()[:2000], receiver_uid=other_uid)
             logger.info("Replied to DM from @%s", other_name)
 
         except (xmlrpc.client.Fault, Exception) as e: