Replace the standalone `?archived=` query parameter on the chats listing
endpoint with a `?q=` search parameter, consistent with how workspaces,
tasks, templates, and other list endpoints work.
The `q` parameter uses the standard `key:value` search syntax parsed by
the `searchquery` package. Currently supports:
- `archived:true/false` (default: `false`, hides archived chats)
When `q` is empty or omits the archived filter, archived chats are
excluded by default. This is a behavioral change — the previous API
returned all chats (including archived) when no filter was specified.
### Changes
**Backend:**
- Add `searchquery.Chats()` parser following the same pattern as
`Tasks()`, `Workspaces()`, etc.
- Update `listChats` handler to read `q` instead of `archived`
- Update `codersdk.ListChatsOptions` to use `Q string` instead of
`Archived *bool`
**Frontend:**
- Update `getChats` API method to accept `q` parameter
- Update `infiniteChats` query to pass `q` instead of `archived`
**Tests:**
- Add `TestSearchChats` unit tests for the parser
- Update existing archive/unarchive integration tests to use `Q:
"archived:true"` syntax
Kyle Carberry
196c6702fd