feat(benchmark): the built-in benchmark, redesigned into the console

The old standalone benchmark.html (Russian-only, Tailwind+Chart.js from CDNs,
never shipped in the crate) becomes a proper sidebar view. Same scoring ideas,
reimplemented: keyword checks with |-synonyms, think-tag stripping, tail-loop
detection, pass/partial/fail — plus what the old page never had: runs go
through the LIVE pipeline (pinned per model, streamed), so every test also
measures tok/s and time-to-first-token with the gateway's real token counts.

A built-in suite of 12 language-neutral probes (math, logic, code, QA,
instruction-following, extraction, translation, JSON formatting); the ⚡ quick
mode runs the 6 short ones — about a minute on a local model. Results: score
bars per model sorted best-first, a per-test grid (click a cell for the full
answer), previous runs and custom tests kept in the browser.

22 new strings in all 7 languages.

web/js/i18n/en.js

@@ -556,4 +556,28 @@ export default {
   "routing.tasks.builtin": "router unreachable — built-in label set",
   "routing.tasks.addCustom": "Add task",
   "routing.tasks.addPlaceholder": "custom label…",
+
+  // benchmark view
+  "nav.benchmark": "Benchmark",
+  "bm.title": "Benchmark",
+  "bm.subtitle": "Quality and speed probes through the live pipeline: keyword-checked answers, anti-loop detection, tok/s and time-to-first-token per model.",
+  "bm.models": "Models to test",
+  "bm.quickMode": "Quick test",
+  "bm.quickHint": "The fast subset with short answers — about a minute per local model.",
+  "bm.suiteInfo": "Built-in suite: {q} quick / {f} full tests, plus your custom ones.",
+  "bm.run": "Run",
+  "bm.pickModel": "Pick at least one model.",
+  "bm.testOf": "test {i} of {n}",
+  "bm.results": "Results",
+  "bm.quick": "quick",
+  "bm.test": "Test",
+  "bm.cellHint": "Click a cell to see the model's full answer.",
+  "bm.history": "Previous runs (stored in this browser)",
+  "bm.custom": "Custom tests",
+  "bm.customHint": "Prompt + comma-separated keywords the answer must contain (use | for synonyms). Stored in this browser.",
+  "bm.promptPh": "prompt…",
+  "bm.checkPh": "keywords, comma-separated",
+  "bm.addTest": "Add test",
+  "bm.emptyAnswer": "empty answer",
+  "bm.loopDetected": "loop detected",
 };