feat(R03): unify provider catalogue, routing decisions and usage telemetry

EPIC R03 (Team Duy) - one provider catalogue, one routing flow, one usage seam.

R03-T01 tests/contracts/test_providers.py
  29 contract tests every provider must satisfy: canonical assistant message,
  streamed text == returned content, reasoning never joins the answer, parsed
  tool arguments, ProviderError for every failure. Real adapters exercised
  offline by stubbing Provider._request.
R03-T02 domain/models/provider_descriptor.py
        infrastructure/providers/provider_registry.py
  Provider facts declared once (was split across providers/factory.py,
  DEFAULT_CONFIG and PROVIDER_LABELS). ProviderRegistry.build() also stamps the
  descriptor id onto the instance, so ollama/github_copilot/codex usage is no
  longer all attributed to "openai_compat", and never mutates the caller config.
R03-T03 application/model_routing/routing_application_service.py
  Pure-Python routing policy with four modes: Off, Auto, Manual and the new
  Fallback (switch only AFTER the current model fails). Depends on a RoutingPort
  protocol; production wires the existing core.routing engine underneath.
R03-T04/T05 ui/chat_panel.py, ui/co4e_tab.py, ui/folder_tab.py
  Three near-identical routing copies (~40 lines each) replaced by a call to
  ctx.routing_application() plus a confirm callback. Mode vocabulary now lives
  in one place (normalize_mode/is_valid_mode) instead of four literal tuples.
R03-T06 infrastructure/telemetry/usage_sink.py
  Token usage extracted from both providers into UsageEvent + UsageEventSink.
  Estimation pinned against core.usage_tracker so no recorded number changes.

Also fixes a deadlock introduced while wiring AppContext: routing_application()
held _routing_lock and called routing(), which takes the same non-reentrant lock.

Suite: 186 passed, 1.22s. check_imports: PASS. All new files < 400 LOC.
2 pre-existing failures remain in test_config_security.py (EPIC R02/Team Nam).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

providers/anthropic.py

@@ -292,21 +292,19 @@ class AnthropicProvider(Provider):
                 args = {"_raw": b["json"]}
             tool_calls.append({"id": b["id"], "name": b["name"], "arguments": args})
 
-        # Dashboard usage event — real counts from the stream's usage events,
-        # else a ~4 chars/token estimate. Never breaks the turn.
-        try:
-            from ..core import usage_tracker as ut
+        # Dashboard usage event — real counts from the stream's usage events
+        # (input arrives on message_start, output on message_delta), else a
+        # ~4 chars/token estimate. Delivery is the sink's job (R03-T06), so this
+        # only translates Anthropic's wire shape into a canonical UsageEvent.
+        from ..infrastructure.telemetry import usage_sink as telemetry
 
-            if usage_seen:
-                ut.record(self.name, self.model, usage_seen.get("in", 0),
-                          usage_seen.get("out", 0), usage_seen.get("cache", 0))
-            else:
-                sent = json.dumps(payload.get("messages", []), ensure_ascii=False)
-                got = "".join(text_parts) + "".join(b["json"] for b in blocks.values())
-                ut.record(self.name, self.model, ut.estimate_tokens(sent),
-                          ut.estimate_tokens(got), 0, estimated=True)
-        except Exception:  # noqa: BLE001
-            pass
+        if usage_seen:
+            event = telemetry.anthropic_usage_event(self.name, self.model, usage_seen)
+        else:
+            sent = json.dumps(payload.get("messages", []), ensure_ascii=False)
+            got = "".join(text_parts) + "".join(b["json"] for b in blocks.values())
+            event = telemetry.estimated_event(self.name, self.model, sent, got)
+        self._emit_usage(event)
 
         return {"role": "assistant", "content": "".join(text_parts), "tool_calls": tool_calls}