feat: M3.8.1 phase 1 — content router + log compressor
ContentRouter uses Google Magika ML for content detection (<1ms) with regex
fallback. Detects JSON, code, logs, diffs, config, text.
LogCompressor reuses M3.7.7 patterns (markers, cascade, strip_ansi) to
shrink build logs by keeping errors/stacks and dropping noise.
17 unit tests passing:
- router: json, code, diff, log, text detection
- log: error lines, stack traces, ansi stripping, compression
- optimizer: token estimation, passthrough mode
Magika + ort ONNX runtime added to Cargo.toml.