Classify network failures (dns/connect/timeout/tls) with distinct exit
codes 2-5. Add --timeout (default 10s) via context.WithTimeout. Add
--fail for exit 6 on HTTP status >= 400. Preserve partial phase timing
up to the failure point. -n sampling continues on network failures,
aggregating successes and reporting fail counts. JSON extended with
succeeded/failed/errors fields.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Sets up project structure, working conventions (CLAUDE.md), README with
the full assignment and roadmap, seeded CHANGELOG, and a buildable Go
scaffold (Step 0) with flag parsing and stub probe types.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
