fix: add archived query parameter to chat list endpoint (#22562)

Despite the SDK type having an `Archived` field for chats, this data was
never fetched from the database — the `GetChatsByOwnerID` query
hardcoded `AND archived = false`, and the `convertChat` function never
mapped the field.

This PR adds an optional `archived` query parameter to `GET
/api/experimental/chats`:

| Value | Behavior |
|-------|----------|
| *(not provided)* | Returns all chats (active and archived) |
| `archived=false` | Returns only non-archived chats |
| `archived=true` | Returns only archived chats |

This follows the same pattern used by template versions
(`sqlc.narg('archived')` nullable boolean).

Also fixes `convertChat` to populate the `Archived` field in API
responses, which was never being set despite existing on the SDK type.

codersdk/chats.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"strings"
 	"time"
 
@@ -501,9 +502,18 @@ type chatStreamEnvelope struct {
 	Data json.RawMessage     `json:"data,omitempty"`
 }
 
+// ListChatsOptions are optional parameters for ListChats.
+type ListChatsOptions struct {
+	Archived *bool
+}
+
 // ListChats returns all chats for the authenticated user.
-func (c *Client) ListChats(ctx context.Context) ([]Chat, error) {
-	res, err := c.Request(ctx, http.MethodGet, "/api/experimental/chats", nil)
+func (c *Client) ListChats(ctx context.Context, opts *ListChatsOptions) ([]Chat, error) {
+	qp := url.Values{}
+	if opts != nil && opts.Archived != nil {
+		qp.Set("archived", fmt.Sprintf("%t", *opts.Archived))
+	}
+	res, err := c.Request(ctx, http.MethodGet, fmt.Sprintf("/api/experimental/chats?%s", qp.Encode()), nil)
 	if err != nil {
 		return nil, err
 	}