refactor: hoist port literal to lib/constants.mjs + CI gate (v3.16.4) (#98)

Closes the structural side of the port-drift cascade addressed by
v3.16.2/v3.16.3. Those releases reverted the literal line-by-line; this
one removes the invitation to drift.

Changes:
  * NEW lib/constants.mjs — exports DEFAULT_PORT=3456, LOCAL_HOST,
    OPENAI_API_BASE, LOCAL_PROXY_URL.
  * server.mjs / setup.mjs / scripts/upgrade.mjs / scripts/doctor.mjs
    (x2) / scripts/sync-openclaw.mjs all import DEFAULT_PORT from
    lib/constants.mjs instead of hardcoding "3456".
  * .github/workflows/alignment.yml:
    - path filter extended to setup.mjs, scripts/**, lib/**,
      ocp, ocp-connect.
    - NEW job port-spot hard-fails any PR that introduces a hardcoded
      "3478" or "3456" literal outside EXEMPT_REGEX (lib/constants.mjs,
      test-features.mjs, ocp/ocp-connect bash CLIs, docs, the workflow
      itself).
  * Doc-comment rewording so CI grep finds zero hits.

No behavior change for any user. CLAUDE_PROXY_PORT env var still wins
at runtime; only the unset-env fallback now flows through one constant.

ALIGNMENT.md note: server.mjs change is one import + one literal swap,
mechanical. No cli.js operation changed; the citation requirement does
not apply.

cli.js: not applicable — mechanical refactor, no behavior change.

Co-authored-by: dtzp555 <dtzp555@gmail.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "open-claude-proxy",
-  "version": "3.16.3",
+  "version": "3.16.4",
   "description": "OCP (Open Claude Proxy) — use your Claude Pro/Max subscription as an OpenAI-compatible API for any IDE. Works with Cline, OpenCode, Aider, Continue.dev, OpenClaw, and more.",
   "type": "module",
   "bin": {