Replace _trace_manager variables with FastAPI dependency injection

[krisztianfekete]

This PR replaces global _trace_manager variables and setter functions with standard FastAPI dependency injection, making the wiring less brittle and tests simpler.

[Copilot]

Pull request overview

This PR migrates trace manager wiring from module-level globals/setters to FastAPI dependency injection via app.state, reducing hidden state and simplifying test setup for OTLP + streaming/debug routes.

Changes:

• Introduces get_trace_manager / require_trace_manager dependencies and injects StreamingTraceManager into OTLP, streaming, and debug endpoints.
• Updates app/OTLP app startup to share the trace manager through app.state.trace_manager instead of setter functions.
• Refactors tests and integration fixtures to pass/set the manager explicitly and patches the new internal helper used by evaluation routes.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/test_otlp_receiver.py	Updates OTLP processing tests to pass mgr explicitly into _process_traces/_process_logs.
tests/test_api.py	Switches live wiring to app.state.trace_manager, updates patches to _do_create_eval_set, and adjusts expected status for debug load when live mode is off.
tests/integration/conftest.py	Sets test_app.state.trace_manager in ASGI fixtures and forwards main app manager into otlp_app for live server tests.
src/agentevals/api/streaming_routes.py	Removes global manager/setter; injects manager via Depends(require_trace_manager) and factors shared eval-set creation into _do_create_eval_set.
src/agentevals/api/otlp_routes.py	Removes _trace_manager global/setter; injects manager via Depends(require_trace_manager) and threads it through processing helpers.
src/agentevals/api/otlp_app.py	Copies trace_manager from main app state into OTLP app state during lifespan.
src/agentevals/api/dependencies.py	Adds FastAPI dependencies for optional/required access to request.app.state.trace_manager.
src/agentevals/api/debug_routes.py	Removes _trace_manager global/setter; injects manager (optional for bundle, required for load).
src/agentevals/api/app.py	Removes trace manager globals/setters; creates/uses app.state.trace_manager in live mode and during lifespan cleanup.

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