test: add OTLP output support to integration tests

[Molter73]

Description

Extend the test infrastructure to support both gRPC and OTLP output modes. Both servers translate their native message format into the test's Event/Process types, keeping protocol-specific code isolated.

Changes:

• Add EventServer base class with shared queue/wait logic
• Add GrpcServer translating FileActivity protobufs into Events
• Add OtlpServer receiving OTLP/HTTP binary protobuf log exports
• Refactor Event.diff() and Process.diff() to compare Event vs Event
• Add --output pytest option (grpc, otlp, all; default: grpc)
• Parameterize server fixture so tests run per output mode
• Add pytest-otlp and pytest-all Makefile targets
• Fix rust_style_quote to match Rust shlex backslash handling
• Add opentelemetry-proto dependency
• Add CARGO_ARGS build arg to Containerfile
• Add image-otel Makefile target

Assisted-by: claude-opus-4-6@default noreply@opencode.ai

Checklist

• Patch has a change log entry OR does not need one.
• Investigated and inspected CI test results
• Updated documentation accordingly

Automated testing

• Added unit tests
• Added integration tests
• Added regression tests

If any of these don't apply, please comment below.

Testing Performed

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✨ Finishing Touches

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• Commit unit tests in branch mauro/tests/otel-support

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 34.13%. Comparing base (b915ce8) to head (e2a1695).

Additional details and impacted files

@@                   Coverage Diff                   @@
##           mauro/feat/otel-output    #1012   +/-   ##
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  Coverage                   34.13%   34.13%           
=======================================================
  Files                          21       21           
  Lines                        2868     2868           
  Branches                     2868     2868           
=======================================================
  Hits                          979      979           
  Misses                       1886     1886           
  Partials                        3        3           

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