Merge origin/master (v0.5.91) into gitea/new_feature

Resolve conflicts:
- streamingHandler.js: adopt upstreamResponseHeaders while keeping 0-token detail row avoidance
- capabilities.js: preserve user-asserted caps and globalThis slots without local caching of catalogSource
- AddCustomModelModal.js & providers/[id]/page.js: wire STT transport marker with custom model edits/assertions
- models/custom/route.js & aliasRepo.js: persist custom model transport and invalidate user caps
- usageRepo.js: key byApiKey live stats by full API key and keep tail in maskApiKey
- UsageStats.js: lazy load charts dynamically

package.json

@@ -1,6 +1,6 @@
 {
   "name": "9router-app",
-  "version": "0.5.86",
+  "version": "0.5.91",
   "description": "9Router web dashboard",
   "private": true,
   "scripts": {