feat(routing): per-task rules on top of complexity tiers; hosted router is the default

The router has always returned two signals — task label and complexity tier —
but only the tier picked models. [routing.tasks] adds `label → ordered models`:
a matching rule's models lead the candidate chain and the tier chain follows as
fallback, so pinning translations to a local model never weakens failover.
Requests whose chain was headed by a task rule report
route_source "router+task-rule".

The Routing page grows a per-task editor built from the account's LIVE
taxonomy (GET /v1/taxonomies via the new /admin/api/routing/labels proxy;
built-in label set when the router is unreachable), with localized task names,
each task's share of 7-day traffic, "by complexity (no rule)" as the explicit
empty state, and custom labels for other taxonomies. Deleting a model scrubs
it from task rules like it always did from tiers.

Also fixes the default config pointing at a placeholder localhost:8080 router
with a nonexistent taxonomy — a fresh install now targets the hosted allaigate
router (IP endpoint, verify_tls off, data-assistant, 12 s oracle timeout) and
degrades gracefully until a key is set. Verified end-to-end against the live
router: translation → task-rule model, math → tier path.

16 new strings in all 7 languages.

web/js/i18n/en.js

@@ -538,4 +538,22 @@ export default {
   "bench.running": "measuring…",
   "bench.failed": "failed",
   "bench.none": "No local .cmf chat models yet.",
+
+  // task-based routing
+  "task.chitchat": "Small talk",
+  "task.code": "Code",
+  "task.creative-writing": "Creative writing",
+  "task.extraction": "Data extraction",
+  "task.math": "Math",
+  "task.qa": "Q&A",
+  "task.summarization": "Summarization",
+  "task.translation": "Translation",
+  "routing.tasks.title": "Task-based routing",
+  "routing.tasks.hint": "A rule's models go first for that task; the complexity chain below still applies as fallback. Empty = route by complexity only.",
+  "routing.tasks.inherit": "by complexity (no rule)",
+  "routing.tasks.share": "{p}% of requests (7d)",
+  "routing.tasks.fromRouter": "labels live from the router",
+  "routing.tasks.builtin": "router unreachable — built-in label set",
+  "routing.tasks.addCustom": "Add task",
+  "routing.tasks.addPlaceholder": "custom label…",
 };