refactor(open-sse): remove reverse coupling open-sse -> src (E2)

Move clineAuth into open-sse/shared (src re-exports back). Add standalone
open-sse/shared/machineId for codex session hashing (no @/lib/dataDir).
sttCore receives sttConfig via param instead of importing AI_PROVIDERS.
No behavior change; gate: no regression (26 known-fails unchanged).

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

open-sse/services/provider.js

@@ -1,5 +1,5 @@
 import { PROVIDERS } from "../config/providers.js";
-import { buildClineHeaders } from "../../src/shared/utils/clineAuth.js";
+import { buildClineHeaders } from "../shared/clineAuth.js";
 
 const OPENAI_COMPATIBLE_PREFIX = "openai-compatible-";
 const OPENAI_COMPATIBLE_DEFAULTS = {