Merge origin/master (v0.5.81) into gitea/new_feature

Resolve conflicts:
- streamingHandler.js: merge buildStreamErrorBytes onAbortTerminal + local shouldPersistRequestDetail & streamStatusForContent
- capabilities.js: preserve server-injected user-asserted caps and models.dev catalog lookup; wire CommandCode /alpha/generate caps inside resolve()
- commandcode.js (services/usage): adopt upstream whoami + billing credits/subscriptions with 5h/weekly rate windows and plan caps
- openai-to-commandcode.js: merge toNativeImageBlock (data-URI & http(s) support) and assistant reasoning_content preservation
- commandcode-to-openai.js: adopt upstream mid-stream error throw for clean retry and abortion
- tests: sync commandcode test suite and exclude .next from vitest config

tests/vitest.config.js

@@ -12,7 +12,7 @@ export default defineConfig({
     // Don't scan into git worktrees nested under .claude/ — they carry their
     // own copies of the test files but lack an installed node_modules (open-sse,
     // etc.), which makes provider imports fail during collection.
-    exclude: ["**/node_modules/**", "**/.claude/**", "**/dist/**"],
+    exclude: ["**/node_modules/**", "**/.claude/**", "**/dist/**", "**/.next/**"],
     // Allow many it.concurrent cases (real provider smoke runs ~50 providers in parallel)
     maxConcurrency: 60,
     // Suppress noisy console output from handlers under test