fix: use SQL-level auth filtering for chat listing (#23159)

## Problem

The chat listing endpoint (`GetChatsByOwnerID`) was using
`fetchWithPostFilter`, which fetches N rows from the database and then
filters them in Go memory using RBAC checks. This causes a pagination
bug: if the user requests `limit=25` but some rows fail the auth check,
fewer than 25 rows are returned even though more authorized rows exist
in the database. The client may incorrectly assume it has reached the
end of the list.

## Solution

Switch to the same pattern used by `GetWorkspaces`, `GetTemplates`, and
`GetUsers`: `prepareSQLFilter` + `GetAuthorized*` variant. The RBAC
filter is compiled to a SQL WHERE clause and injected into the query
before `ORDER BY`/`LIMIT`, so the database returns exactly the requested
number of authorized rows.

Additionally, `GetChatsByOwnerID` is renamed to `GetChats` with
`OwnerID` as an optional (nullable) filter parameter, matching the
`GetWorkspaces` naming convention.

## Changes

| File | Change |
|------|--------|
| `queries/chats.sql` | Renamed to `GetChats`, `owner_id` now optional
via CASE/NULL, added `-- @authorize_filter` |
| `queries.sql.go` | Renamed constant, params struct (`GetChatsParams`),
and method |
| `querier.go` | Interface method renamed |
| `modelqueries.go` | Added `chatQuerier` interface +
`GetAuthorizedChats` impl |
| `dbauthz/dbauthz.go` | `GetChats` now uses `prepareSQLFilter` instead
of `fetchWithPostFilter` |
| `dbauthz/dbauthz_test.go` | Updated tests for SQL filter pattern |
| `dbmock/dbmock.go` | Renamed + added mock for `GetAuthorizedChats` |
| `dbmetrics/querymetrics.go` | Renamed + added metrics wrapper |
| `rbac/regosql/configs.go` | Added `ChatConverter` (maps `org_owner` to
empty string literal since `chats` has no `organization_id` column) |
| `rbac/authz.go` | Added `ConfigChats()` |
| `chats.go` | Handler uses renamed method with `uuid.NullUUID` |
| `searchquery/search.go` | Updated return type |
| `gitsync/worker.go` | Updated interface and call site |
| Various test files | Updated for renamed types |

coderd/database/modelqueries.go

@@ -52,6 +52,7 @@ type customQuerier interface {
 	auditLogQuerier
 	connectionLogQuerier
 	aibridgeQuerier
+	chatQuerier
 }
 
 type templateQuerier interface {
@@ -738,6 +739,68 @@ func (q *sqlQuerier) CountAuthorizedConnectionLogs(ctx context.Context, arg Coun
 	return count, nil
 }
 
+type chatQuerier interface {
+	GetAuthorizedChats(ctx context.Context, arg GetChatsParams, prepared rbac.PreparedAuthorized) ([]Chat, error)
+}
+
+func (q *sqlQuerier) GetAuthorizedChats(ctx context.Context, arg GetChatsParams, prepared rbac.PreparedAuthorized) ([]Chat, error) {
+	authorizedFilter, err := prepared.CompileToSQL(ctx, rbac.ConfigChats())
+	if err != nil {
+		return nil, xerrors.Errorf("compile authorized filter: %w", err)
+	}
+
+	filtered, err := insertAuthorizedFilter(getChats, fmt.Sprintf(" AND %s", authorizedFilter))
+	if err != nil {
+		return nil, xerrors.Errorf("insert authorized filter: %w", err)
+	}
+
+	// The name comment is for metric tracking
+	query := fmt.Sprintf("-- name: GetAuthorizedChats :many\n%s", filtered)
+	rows, err := q.db.QueryContext(ctx, query,
+		arg.OwnerID,
+		arg.Archived,
+		arg.AfterID,
+		arg.OffsetOpt,
+		arg.LimitOpt,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Chat
+	for rows.Next() {
+		var i Chat
+		if err := rows.Scan(
+			&i.ID,
+			&i.OwnerID,
+			&i.WorkspaceID,
+			&i.Title,
+			&i.Status,
+			&i.WorkerID,
+			&i.StartedAt,
+			&i.HeartbeatAt,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+			&i.ParentChatID,
+			&i.RootChatID,
+			&i.LastModelConfigID,
+			&i.Archived,
+			&i.LastError,
+			&i.Mode,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 type aibridgeQuerier interface {
 	ListAuthorizedAIBridgeInterceptions(ctx context.Context, arg ListAIBridgeInterceptionsParams, prepared rbac.PreparedAuthorized) ([]ListAIBridgeInterceptionsRow, error)
 	CountAuthorizedAIBridgeInterceptions(ctx context.Context, arg CountAIBridgeInterceptionsParams, prepared rbac.PreparedAuthorized) (int64, error)