fix: detect secure socket when connection is missing

[raashish1601]

Changes

• Update secure-request detection to fall back to req.socket.encrypted when req.connection is missing.
• Preserve existing req.connection precedence while supporting environments where only req.socket is available.
• Add regression test under session() cookie security behavior: treat request as secure when connection is missing but socket.encrypted is true.

Validation

• npm run lint
• npx mocha --require test/support/env --check-leaks --no-exit --reporter spec test/