fix(security): sanitize test regex and annotate CodeQL hash false-positives (#10380)

* fix(security): sanitize test regex and annotate CodeQL hash false-positives

tests/unit/early-sse-route-intent.test.ts built a RegExp from a hardcoded
string but only escaped `?`/`.`, missing `\` — js/incomplete-sanitization
(#816). Not exploitable (fixed literal input) but the escaping was
genuinely incomplete; now escapes backslash too.

reasoningCache.ts::buildAssistantMessageCacheKey and codexIdentity.ts's two
UUID derivation helpers hash a cache-scope/account-seed with SHA-256 to
produce a lookup key / deterministic ID — not a stored, verified password.
CodeQL's js/insufficient-password-hash overfires on any hash of a
secret-like variable, the same false-positive class already annotated at
src/lib/db/apiKeys.ts:624. Added matching lgtm/nosemgrep annotations and
inline rationale so the intent is clear to reviewers and future scans.

Refs #815 #816 #817 #818

* fix(security): keep only the regex sanitization; drop non-functional CodeQL annotations

The lgtm[]/nosemgrep: comments in codexIdentity.ts and reasoningCache.ts use
formats GitHub Actions CodeQL does not honor, and shifting those sha256 lines
re-attributed the already-dismissed base alerts to this PR as two new CodeQL
findings. Revert those two annotation-only files to base so the existing
dismissals apply; retain the real fix (escaping backslash in the test regex),
which resolves the open js/incomplete-sanitization alert.

---------

Co-authored-by: Xiangzhe <bakryun0718@proton.me>
Co-authored-by: adevwithpurpose <adevwithpurpose@users.noreply.github.com>

tests/unit/early-sse-route-intent.test.ts

@@ -22,7 +22,7 @@ const ROUTES = [
 
 for (const route of ROUTES) {
   test(`${route.name} early-heartbeat gate uses the real stream resolver`, () => {
-    const escapedBodyExpression = route.bodyExpression.replace(/[?.]/g, "\\$&");
+    const escapedBodyExpression = route.bodyExpression.replace(/[.?\\]/g, "\\$&");
     assert.match(
       route.source,
       new RegExp(