feat: improve CLI and web API validation with clearer runtime errors

[rad1092]

Motivation

• Improve usability and robustness by surfacing clear, user-facing errors for common operator mistakes like missing CSV files and malformed API parameters.
• Harden the local UI API against abusive or accidental inputs by validating timeout values and CSV payload sizes to avoid confusing runtime failures.

Description

• Convert analysis failures into a friendly exit message in the CLI by catching AnalysisError and FileNotFoundError in run_analyze and raising SystemExit with analysis error: ... instead of a raw traceback (bitnet_tools/cli.py).
• Add stricter timeout parsing and bounds checking for the web API POST /api/run so non-integer timeout values are rejected and values outside 1..600 seconds return a clear HTTP error (bitnet_tools/web.py).
• Add a regression test to assert the CLI path for a missing CSV file fails with a clear SystemExit message and expand tests exercising CSV parsing and summarization (tests/test_analysis.py).

Testing

• Ran unit tests with python -m pytest -q, which returned 6 passed.
• Verified CLI behavior with python -m bitnet_tools.cli analyze /tmp/does-not-exist.csv --question '점검' --out /tmp/nope.json, which exited with a friendly analysis error: CSV file not found and non-zero status.
• Performed a web API smoke test by POSTing an invalid timeout (e.g. `

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Codex Task

[chatgpt-codex-connector]

💡 Codex Review

First_two/bitnet_tools/analysis.py

Line 162 in fa073d3

"std": float(pstdev(values)) if len(values) > 1 else 0.0,

Guard numeric stats against NaN/Infinity inputs

Values like NaN or inf are accepted as numeric and flow into summary statistics, but statistics.pstdev fails on non-finite numbers (ValueError/OverflowError), which crashes analysis for otherwise common CSV markers. This means build_analysis_payload can terminate with a traceback instead of returning a user-facing analysis error whenever a numeric column includes these tokens.

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First_two/bitnet_tools/web.py

Line 66 in fa073d3

content_length = int(self.headers.get("Content-Length", "0"))

Validate Content-Length before converting to int

do_POST converts Content-Length with int(...) outside the request-validation try blocks, so a malformed header such as Content-Length: abc raises ValueError and aborts the handler thread instead of returning a 4xx JSON error. This makes malformed requests bypass the API's intended error handling path and produce server-side exceptions.

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