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/templates/project_detail.html

@@ -94,6 +94,8 @@
                     <input type="hidden" name="value" value="{{ 0 if read_only else 1 }}">
                     <button type="submit" data-confirm-danger data-confirm="{% if read_only %}Allow file changes again for this project?{% else %}Make this project read-only? Files become immutable until you turn this off.{% endif %}" data-menu-action data-menu-icon="{% if read_only %}&#x1F4DD;{% else %}&#x1F6AB;{% endif %}" data-menu-label="{% if read_only %}Allow edits{% else %}Make read-only{% endif %}">{% if read_only %}Allow edits{% else %}Make read-only{% endif %}</button>
                 </form>
+                {% endif %}
+                {% if is_owner or is_admin(user) %}
                 <form method="POST" action="/projects/delete/{{ project['slug'] or project['uid'] }}">
                     <button type="submit" data-confirm-danger data-confirm="Delete this project?" data-menu-action data-menu-icon="&#x1F5D1;&#xFE0F;" data-menu-label="Delete">Delete</button>
                 </form>