Run summaries

Add --summary to write a machine-readable JSON report:

seqproc run ... --summary report.json --statistics-level basic

Statistics are disabled in ordinary runs. Requesting a summary enables them; without an explicit level, summaries default to detailed.

Basic statistics

--statistics-level basic records run-level information with minimal data-dependent instrumentation, including:

• input, accepted, and rejected fragment totals;
• parse failures and categorized rejection reasons;
• effective transform thread count and ordering mode;
• gzip input/output backend parameters;
• seqproc version, command, and geometry digest when available.

Detailed statistics

The default detailed report adds:

• input read-length minima, maxima, and means;
• ordered match-stage attempts, matches, and attrition;
• match-distance distributions;
• equal-best ambiguity counts and policy outcomes.

Detailed collection uses per-thread counters and aggregates at the end of the run, but it is still instrumentation. Benchmark statistics-disabled execution for a headline performance result and measure summary overhead separately.

Schema versioning

The current source tree emits summary schema 1.3.0. Schemas are versioned independently from the binary and are committed under schemas/.

Consumers should inspect schema_version instead of assuming that all seqproc revisions emit the same fields. Additive fields require a schema minor version; removing fields or changing their meaning requires a major version.

The geometry digest is a content/provenance identifier, not a security primitive. Archive the geometry itself and all referenced maps or whitelists in addition to the report.