DC-020: mark done — fixed last broken require in server.js

BACKLOG.md

@@ -10,9 +10,10 @@
 ## P0 — Must Fix (blocks public release)
 
 ### DC-020: Restore deleted license-keygen.js — production container in crash-restart loop
-- **status:** in-progress
+- **status:** done
 - **owner:** hermes
 - **details:** The `refactor(desloppify)` commit (a2e6566) deleted `dashcaddy-api/license-keygen.js` believing it was "stale dev-root noise." It is NOT — it is a required production module. `src/managers/license-manager.js:17` does `require('./license-keygen')` and imports `verifyCode`, `parseCode`, `VALID_DURATIONS` from it. After deletion, `require('./src/app')` throws `MODULE_NOT_FOUND: Cannot find module './license-keygen'` and the **production `dashcaddy-api` Docker container is in a crash-restart loop** (verified: `docker ps` shows `Restarting (1)`, `docker logs` shows the MODULE_NOT_FOUND stack from `/app/src/app.js` → `/app/server.js`). The 1036-test Jest suite never caught this because the only "app-loading" tests read `src/app.js` as a *string* (via `path.join(...,'src','app.js')`), they never execute `require()` on it. Fix: restore the file from git history to `src/managers/license-keygen.js` (the path the post-DC-005 require resolves to) and add a real startup smoke test that executes `require()` on the app module so this class of bug is caught.
+- **result:** Done across two sessions. (1) Restored `license-keygen.js` from git history. (2) Fixed every `require('../src/...')` → `require('./src/...')` in `server.js` — from the production entry point `/app/server.js`, `../src/` resolves to `/src/` (outside the app) instead of `/app/src/`. (3) **Session 2 (this commit f94b164): found and fixed the LAST one the sweep missed** — `server.js:73` still had `require('./state-manager')` which resolves to `/app/state-manager.js`, a file that does NOT exist (module lives at `src/managers/state-manager.js`). Unlike the optional modules below it, this require is bare (no try/catch), so MODULE_NOT_FOUND throws out of the top-level startup IIFE and crash-loops the container — the exact same failure mode. Fixed to `./src/managers/state-manager` (matches line 146). (4) Hardened the regression guard `app-startup-smoke.test.js`: added a static check that EVERY relative `require()` in `server.js` resolves to a real file on disk (server.js can't be require()'d at test time because its IIFE binds port 3001 + starts interval modules). This test would have failed on the original `./state-manager` line, so the whole entry-point path-bug class is now caught. 1067/1067 tests pass, zero new ESLint warnings.
 
 ### DC-012: Add Kubernetes-style /healthz + /readyz probe aliases + document for fresh users
 - **status:** done