AI: swap to regex from pyparsing

[JacobCoffee]

Testing against 1.1 GB of real traffic, (~290 files. 1,000,000 real production lines.)

REAL PRODUCTION TRAFFIC DIFFERENTIAL
- lines compared : 1,000,000
- MISMATCHES     : 0
- rejected (old) : 0  (0.0000%)
- rejected (new) : 0  (0.0000%)

- old parser:  158.95 us/line
- new parser:   43.80 us/line   ->  3.6x

280 real log files pulled from gs://linehaul-logs, both parsers run over every line, comparing full result repr and exception type. Byte-for-byte identical. Combined with the 313k synthetic differential and the 130-test suite, that's the decisive check you asked for.

By Claude robot

Testing some other options

┌───────────────────┬─────────┬─────────┬───────────┬───────────────────────────┐
│      variant      │ us/line │ vs main │ vs PR 322 │ CPU per 55k-line log file │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ pyparsing (main)  │   151.5 │    1.0× │           │                      8.3s │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ regex (PR 322)    │    44.5 │    3.4× │      1.0× │                      2.4s │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ regex, tuned      │    17.2 │    8.8× │      2.6× │                     0.95s │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ pyo3 rust         │    5.97 │   25.4× │      7.5× │                     0.33s │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ pure rust         │    5.46 │   27.8× │      8.2× │                     0.30s │
├───────────────────┼─────────┼─────────┼───────────┼───────────────────────────┤
│ pure rust + rayon │    1.36 │    111× │     32.7× │                    0.075s │
└───────────────────┴─────────┴─────────┴───────────┴───────────────────────────┘