Actually run eslint in CI

.github/workflows/deploy.yml

@@ -180,6 +180,22 @@ jobs:
         working-directory: frontend
         run: npm audit --audit-level=high --omit=dev
 
+      # ESLint. This step did not exist until 2026-09-11, which made
+      # `eslint.config.js` decorative: the config was added specifically
+      # to fix `npm run lint` silently erroring with "couldn't find a
+      # config", and then nothing ever ran it. Thirteen errors
+      # accumulated in master unnoticed, and the eslint 9 -> 10 bump was
+      # reviewed by running the linter by hand because CI could not say
+      # anything about it.
+      #
+      # eslint exits non-zero on errors only, so the ~34 deliberate
+      # `warn`-level findings (React Compiler advisories, unused-vars)
+      # stay visible in the log without blocking a deploy. That split is
+      # the whole point — see the rule notes in eslint.config.js.
+      - name: Lint (eslint)
+        working-directory: frontend
+        run: npm run lint
+
       # Vitest component tests — run BEFORE the build so a regression
       # caught by tests doesn't get the chance to ship via a successful
       # build.  We have ~50 tests today (HelpTooltip, InstallCameraNodeCard,

frontend/eslint.config.js

@@ -90,6 +90,25 @@ export default [
       "react-hooks/purity": "warn",
       "react-hooks/refs": "warn",
       "react-hooks/preserve-manual-memoization": "warn",
+      // Same family, same reasoning — these two were missed when the
+      // list above was written, and they were the only thing keeping
+      // `npm run lint` at a non-zero exit:
+      //
+      // - `immutability` fires 12 times on the shape
+      //   `useEffect(() => { loadThings() }, [...])` where `loadThings`
+      //   is a `const` arrow function declared further down the
+      //   component. It is correct at runtime — effects run after
+      //   render, by which point the binding is initialized — so this
+      //   is the compiler saying it cannot track the value, not a live
+      //   bug. The fix is to hoist each loader above its effect (or
+      //   wrap in useCallback), which is a real change to six files and
+      //   belongs with the next edit to each.
+      // - `use-memo` fires once, on a non-inline first argument.
+      //
+      // Kept at `warn` rather than disabled: the diagnostic stays in
+      // the CI log, and lint can now be enforcing for everything else.
+      "react-hooks/immutability": "warn",
+      "react-hooks/use-memo": "warn",
     },
   },