feat(lint): add no-unused-vars ratchet scoped to src+open-sse+tests (#11247)

Validated on the combined 12-PR batch board: typecheck:core clean, file-size/changelog/complexity/cognitive gates within baseline, eslint config smoke-tested. Freeze-then-ratchet for @typescript-eslint/no-unused-vars scoped to src/open-sse/tests (1393 pre-existing frozen, _ escape hatch, args:all), following the #7879 pattern — plus it untracks the two docs/superpowers planning files that leaked in via #11213 and were tripping check:tracked-artifacts for everyone. Thank you @maxmad64bis!

changelog.d/maintenance/11247-ratchet-no-unused-vars.md

@@ -0,0 +1 @@
+- **chore(lint):** ratchet `@typescript-eslint/no-unused-vars` scoped to `src/` + `open-sse/` + `tests/` (`args: "all"`, `_`-prefix escape hatch) and freeze the 1393 pre-existing violations via bulk suppressions — same pattern as the #7879 `toNumber` ratchet. New unused bindings now fail lint. ([#11247](https://github.com/diegosouzapw/OmniRoute/pull/11247))

eslint.config.mjs

@@ -145,6 +145,31 @@ const eslintConfig = [
       "react-hooks/rules-of-hooks": "off",
     },
   },
+  // Ratchet: bar NEW unused vars/args/catches outside the `_` escape hatch.
+  // Pre-existing violations are frozen via config/quality/eslint-suppressions.json
+  // (same pattern as #7879 toNumber); only genuinely NEW unused bindings fail
+  // lint. `args: "all"` (not `after-used`) so a leading unused param is never
+  // silently skipped, e.g. `function handle(req, _opts, next)` must flag `req`.
+  {
+    files: ["src/**/*.{ts,tsx,js,jsx}", "open-sse/**/*.ts", "tests/**/*.{ts,tsx,mjs}"],
+    plugins: {
+      "@typescript-eslint": tseslint.plugin,
+    },
+    rules: {
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          args: "all",
+          argsIgnorePattern: "^_",
+          varsIgnorePattern: "^_",
+          caughtErrors: "all",
+          caughtErrorsIgnorePattern: "^_",
+          destructuredArrayIgnorePattern: "^_",
+          ignoreRestSiblings: true,
+        },
+      ],
+    },
+  },
   // Global ignores — keep ESLint scoped to source files only
   {
     ignores: [