fix(translator): ESM-safe registry + tool-id pairing + responses max_tokens; add real-creds tests

- translator/index.js: replace require() with static side-effect imports (ESM-safe),
  lazy-init registry maps to survive circular import order
- openai-responses->openai: map max_output_tokens -> max_tokens (avoid leaking field upstream)
- gemini/antigravity -> openai: derive deterministic tool_call id from name so
  functionCall/functionResponse pair correctly (fixes provider tool-pairing 400s)
- add offline unit tests (finish-reason, usage, session-manager, ollama malformed args, const guard)
- add real-creds integration tests (provider-cases + all-formats matrix: 6 inbound formats x 4 scenarios)

Includes co-located provider registry refactor (pricing/capabilities/media providers) and sessionManager updates.

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/executors/antigravity.js

@@ -3,7 +3,7 @@ import { BaseExecutor } from "./base.js";
 import { PROVIDERS } from "../config/providers.js";
 import { OAUTH_ENDPOINTS, ANTIGRAVITY_HEADERS, INTERNAL_REQUEST_HEADER, AG_DEFAULT_TOOLS, AG_TOOL_SUFFIX } from "../config/appConstants.js";
 import { HTTP_STATUS } from "../config/runtimeConfig.js";
-import { deriveSessionId } from "../utils/sessionManager.js";
+import { resolveSessionId } from "../utils/sessionManager.js";
 import { proxyAwareFetch } from "../utils/proxyFetch.js";
 import { cleanJSONSchemaForAntigravity } from "../translator/formats/gemini.js";
 
@@ -94,7 +94,7 @@ export class AntigravityExecutor extends BaseExecutor {
       generationConfig,
       ...(contents && { contents }),
       ...(tools && { tools }),
-      sessionId: body.request?.sessionId || deriveSessionId(credentials?.email || credentials?.connectionId),
+      sessionId: body.request?.sessionId || resolveSessionId({ headers: credentials?.rawHeaders, body, connectionId: credentials?.email || credentials?.connectionId, scope: "antigravity" }),
       safetySettings: undefined,
       ...(tools?.length > 0 && { toolConfig: { functionCallingConfig: { mode: "VALIDATED" } } })
     };