feat(cherry-pick): fixes for 0.3.1 release (#3998)

## Summary

Cherry-picks 5 critical fixes from main to the release-0.3.x branch for
the v0.3.1 release, plus CI workflow updates.

**Note**: This recreates the cherry-picks from the closed PR #3991, now
targeting the renamed `release-0.3.x` branch (previously
`release-0.3.x-maint`).

## Commits

1. **2c56a8560** - fix(context): prevent provider data leak between
streaming requests (#3924)
- **CRITICAL SECURITY FIX**: Prevents provider credentials from leaking
between requests
   - Fixed import path for 0.3.0 compatibility

2. **ddd32b187** - fix(inference): enable routing of models with
provider_data alone (#3928)
   - Enables routing for fully qualified model IDs with provider_data
   - Resolved merge conflicts, adapted for 0.3.0 structure

3. **f7c2973aa** - fix: Avoid BadRequestError due to invalid max_tokens
(#3667)
- Fixes failures with Gemini and other providers that reject
max_tokens=0
   - Non-breaking API change

4. **d7f9da616** - fix(responses): sync conversation before yielding
terminal events in streaming (#3888)
- Ensures conversation sync executes even when streaming consumers break
early

5. **0ffa8658b** - fix(logging): ensure logs go to stderr, loggers obey
levels (#3885)
   - Fixes logging infrastructure

6. **75b49cb3c** - ci: support release branches and match client branch
(#3990)
   - Updates CI workflows to support release-X.Y.x branches
- Matches client branch from llama-stack-client-python for release
testing
   - Fixes artifact name collisions

## Adaptations for 0.3.0

- Fixed import paths: `llama_stack.core.telemetry.tracing` →
`llama_stack.providers.utils.telemetry.tracing`
- Fixed import paths: `llama_stack.core.telemetry.telemetry` →
`llama_stack.apis.telemetry`
- Changed `self.telemetry_enabled` → `self.telemetry` (0.3.0 attribute
name)
- Removed `rerank()` method that doesn't exist in 0.3.0

## Testing

All imports verified and tests should pass once CI is set up.

.github/workflows/integration-vector-io-tests.yml

@@ -4,9 +4,13 @@ run-name: Run the integration test suite with various VectorIO providers
 
 on:
   push:
-    branches: [ main ]
+    branches:
+      - main
+      - 'release-[0-9]+.[0-9]+.x'
   pull_request:
-    branches: [ main ]
+    branches:
+      - main
+      - 'release-[0-9]+.[0-9]+.x'
     paths:
       - 'llama_stack/**'
       - '!llama_stack/ui/**'