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/openai_compat.py

@@ -268,22 +268,25 @@ class OpenAICompatProvider(Provider):
     def _record_usage(self, messages, text_parts, tool_acc, usage_seen) -> None:
         """One Dashboard usage event per turn: real counts when the server's
         final chunk carried a "usage" block, a ~4 chars/token estimate
-        otherwise. Never breaks the turn."""
-        try:
-            from ..core import usage_tracker as ut
+        otherwise.
 
-            if usage_seen:
-                ut.record(self.name, self.model,
-                          usage_seen.get("prompt_tokens", 0),
-                          usage_seen.get("completion_tokens", 0),
-                          (usage_seen.get("prompt_tokens_details") or {}).get("cached_tokens", 0))
-            else:
-                sent = json.dumps(self._to_api_messages(messages), ensure_ascii=False)
-                got = "".join(text_parts) + "".join(s["args"] for s in tool_acc.values())
-                ut.record(self.name, self.model, ut.estimate_tokens(sent),
-                          ut.estimate_tokens(got), 0, estimated=True)
-        except Exception:  # noqa: BLE001
-            pass
+        Building the event and delivering it are now separate concerns (R03-T06):
+        this method only translates THIS provider's wire shape into a canonical
+        ``UsageEvent``; where it ends up is the sink's decision, so a test can
+        assert on token counts without writing to the real Dashboard store."""
+        from ..infrastructure.telemetry import usage_sink as telemetry
+
+        if usage_seen:
+            event = telemetry.openai_usage_event(self.name, self.model, usage_seen)
+        else:
+            # No usage block from the gateway (self-hosted servers and Ollama
+            # never send one) - fall back to estimating from the raw text of
+            # both directions, tool-call arguments included since the model was
+            # billed for generating them.
+            sent = json.dumps(self._to_api_messages(messages), ensure_ascii=False)
+            got = "".join(text_parts) + "".join(s["args"] for s in tool_acc.values())
+            event = telemetry.estimated_event(self.name, self.model, sent, got)
+        self._emit_usage(event)
 
     def list_models(self):
         self.last_error = ""