fix(providers): route OrcaRouter chat requests to /v1/chat/completions (#11923)

Boarded with 8 other PRs in one combined worktree: typecheck:core, check:file-size, check:changelog-integrity, check:complexity, check:cognitive-complexity, check:cycles, check-native-deps all green. Retargeted from main to release/v3.8.51. One-line baseUrl fix with a live endpoint probe documenting the exact 404→401 transition — solid verification. Thanks.

changelog.d/fixes/11923-orcarouter-baseurl.md

@@ -0,0 +1 @@
+- **fix(providers):** OrcaRouter chat requests now target `/v1/chat/completions` instead of the bare `/v1` API root, fixing the upstream `404 Invalid URL (POST /v1)` ([#11923](https://github.com/diegosouzapw/OmniRoute/pull/11923)).

open-sse/config/providers/registry/orcarouter/index.ts

@@ -13,7 +13,7 @@ export const orcarouterProvider: RegistryEntry = {
   alias: "orcarouter",
   format: "openai",
   executor: "default",
-  baseUrl: "https://api.orcarouter.ai/v1",
+  baseUrl: "https://api.orcarouter.ai/v1/chat/completions",
   authType: "apikey",
   authHeader: "bearer",
   defaultContextLength: 128000,