test: add independent log parser fixtures

[GioLealhmx]

/claim #5

Summary

Fixes #5 by adding independent, fixture-backed coverage for the legacy log aggregator parsers. The new fixtures are handwritten production-like samples for JSON, plain text, nginx access logs, and malformed/unsupported input, so the tests no longer depend on data generated by the parser itself.

The independent nginx fixture exposed two small parser bugs, which this PR fixes: nginx lines now reach the nginx parser before the generic text fallback, and remote_user now maps to the nginx remote user field instead of the ident field.

Changes

• Added independent log fixtures under tools/tests/fixtures/log_aggregator/ for JSON, text, nginx, and malformed lines.
• Added tools/tests/test_log_aggregator_fixtures.py using only the Python standard library/unittest.
• Validated parser outputs for timestamp, level, service, message, nginx status, remote address, remote user, and CLI JSON report shape.
• Reordered parser fallback so NginxLogParser runs before TextLogParser.
• Fixed nginx remote_user extraction to use the correct regex group.
• Hardened build.py so missing optional toolchains are reported as module failures instead of aborting before diagnostics are generated.

Testing

• python -m py_compile build.py tools/log_aggregator.py — PASS
• python -m unittest discover -s tools/tests -p "test_*.py" -v — PASS, 5 tests
• python build.py — ran and generated required diagnostics: diagnostic/build-a17cdea5.logd and diagnostic/build-a17cdea5-metadata.json. Exit code was 1 because this Windows environment lacks several unrelated toolchains; the diagnostic metadata records 2 passed modules (market, compliance) and 8 missing-toolchain failures.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

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• I would like to request that my diagnostic build log is removed before merging

[GioLealhmx]

Hi maintainers — the required GitHub Actions workflow for this fork PR is currently showing action_required, so it looks like it needs maintainer approval before CI can run.

Local verification is documented in the PR body:

• python -m py_compile build.py tools/log_aggregator.py — PASS
• python -m unittest discover -s tools/tests -p "test_*.py" -v — PASS
• python build.py — generated the required diagnostic artifacts; unrelated modules that need unavailable local toolchains are recorded in the diagnostic metadata

Could you please approve the workflow run when convenient? I’ll follow up if CI reports anything actionable.

[GioLealhmx]

Hi maintainers — the required GitHub Actions workflow for this fork PR is currently showing action_required, so it looks like it needs maintainer approval before CI can run.

Local verification is documented in the PR body:

• python -m py_compile build.py tools/log_aggregator.py — PASS
• python -m unittest discover -s tools/tests -p "test_*.py" -v — PASS
• python build.py — generated the required diagnostic artifacts; unrelated modules that need unavailable local toolchains are recorded in the diagnostic metadata

Could you please approve the workflow run when convenient? I’ll follow up if CI reports anything actionable.