SCIX-752: Fix verify middleware crash and implement cross-domain session synchronization

[thostetler]

Users clicking email verification links crashed with "Cannot read property 'access_token' of undefined" because the verify middleware tried to access session.token.access_token without checking if the token existed.

• Added defensive null check in verifyMiddleware before accessing session token
• Fixed hash encoding to use hex format (prevents potential collisions)
• Fixed apiCookieHash null check to match actual return value

Cookie synchronization now properly handles cross-domain session sharing between BBB and Scix:

• Domain attribute stripped (host-only, more secure)
• SameSite forced to lax (allows cross-site navigation, prevents CSRF)
• Only syncs when cookie value actually changes (prevents race conditions)

Deployment Note

⚠️ Hash encoding fix will invalidate existing sessions - users must re-authenticate after deployment.

[codecov]

Codecov Report

❌ Patch coverage is 27.65957% with 68 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.7%. Comparing base (6fcc443) to head (fd6cc7f).

Files with missing lines	Patch %	Lines
src/middlewares/initSession.ts	29.0%	59 Missing ⚠️
src/middlewares/verifyMiddleware.ts	10.0%	9 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #736     +/-   ##
========================================
- Coverage    69.9%   69.7%   -0.1%     
========================================
  Files         220     219      -1     
  Lines       24478   24509     +31     
  Branches     1304    1303      -1     
========================================
- Hits        17086   17066     -20     
- Misses       7357    7408     +51     
  Partials       35      35             

Files with missing lines	Coverage Δ
src/middleware.ts	37.9% <100.0%> (ø)
src/middlewares/verifyMiddleware.ts	15.5% <10.0%> (-1.2%)	⬇️
src/middlewares/initSession.ts	30.9% <29.0%> (-2.1%)	⬇️

... and 3 files with indirect coverage changes

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