feat(kiro): headless API-key auth + direct Claude/Kiro route

Adds long-lived API-key (ksk_) authentication for Kiro/AWS CodeWhisperer
and a direct claude:kiro / kiro:claude translation route that avoids the
lossy OpenAI two-hop pivot.

- translator: claude-to-kiro request + kiro-to-claude response translators,
  registered on the exact source:target pair (direct route ahead of the
  OpenAI pivot in index.js). claude-to-kiro uses shared schema constants
  (ROLE/CLAUDE_BLOCK/DEFAULT_IMAGE_MIME) per app convention.
- auth: POST /api/oauth/kiro/api-key imports + validates a key via
  ListAvailableProfiles, persists authMethod="api_key" (no refresh token).
- executor: send tokentype: API_KEY header and try *.amazonaws.com hosts
  first for api-key creds; OAuth keeps kiro.dev first.
- fix: never inject the default placeholder profileArn for api-key auth
  (CodeWhisperer 403s an ARN not owned by the key's account).
- ui: API Key method in the Kiro connect modal; surface api-key accounts
  on the Quota Tracker and provider count.
- stream: env-overridable TTFT vs stall timeouts + Kiro keepalive frame.
- tests: claude-kiro-direct + kiro-profile-arn (11 tests).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/providers/client/route.js

@@ -17,6 +17,7 @@ const SAFE_PSD_FIELDS = [
   "connectionProxyEnabled", "connectionProxyUrl", "connectionNoProxy",
   "githubLogin", "githubName", "githubEmail", "githubUserId",
   "username", "firstName", "lastName", "authMethod", "authKind",
+  "profileArn",
 ];
 
 const DEFAULT_PAGE_SIZE = 20;