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.

tests/unit/core/test_provider_data_context.py

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import asyncio
+import json
+from contextlib import contextmanager
+from contextvars import ContextVar
+
+from llama_stack.core.utils.context import preserve_contexts_async_generator
+
+# Define provider data context variable and context manager locally
+PROVIDER_DATA_VAR = ContextVar("provider_data", default=None)
+
+
+@contextmanager
+def request_provider_data_context(headers):
+    val = headers.get("X-LlamaStack-Provider-Data")
+    provider_data = json.loads(val) if val else {}
+    token = PROVIDER_DATA_VAR.set(provider_data)
+    try:
+        yield
+    finally:
+        PROVIDER_DATA_VAR.reset(token)
+
+
+def create_sse_event(data):
+    return f"data: {json.dumps(data)}\n\n"
+
+
+async def sse_generator(event_gen_coroutine):
+    event_gen = await event_gen_coroutine
+    async for item in event_gen:
+        yield create_sse_event(item)
+        await asyncio.sleep(0)
+
+
+async def async_event_gen():
+    async def event_gen():
+        yield PROVIDER_DATA_VAR.get()
+
+    return event_gen()
+
+
+async def test_provider_data_context_cleared_between_sse_requests():
+    headers = {"X-LlamaStack-Provider-Data": json.dumps({"api_key": "abc"})}
+    with request_provider_data_context(headers):
+        gen1 = preserve_contexts_async_generator(sse_generator(async_event_gen()), [PROVIDER_DATA_VAR])
+
+    events1 = [event async for event in gen1]
+    assert events1 == [create_sse_event({"api_key": "abc"})]
+    assert PROVIDER_DATA_VAR.get() is None
+
+    gen2 = preserve_contexts_async_generator(sse_generator(async_event_gen()), [PROVIDER_DATA_VAR])
+    events2 = [event async for event in gen2]
+    assert events2 == [create_sse_event(None)]
+    assert PROVIDER_DATA_VAR.get() is None