chore: fleet hygiene — README badges + go.mod 1.22 alignment

[NovaLux12]

Summary

• Add standard badges row (CI, Release, Go version, License MIT) to README, matching the cron-doctor / fleet-pulse sibling style with repo name swapped.
• Downgrade go.mod go directive from 1.26 to 1.22 per fleet convention.

Safety check for downgrade

Audited all Go sources for post-1.22 stdlib usage: imports are limited to pre-1.22 stdlib (bytes, encoding/json, errors, flag, fmt, html/template, io, math, os, os/exec, path/filepath, sort, strings, testing, time). No unique/iter/weak/math\/rand\/v2/slices/maps/cmp usage; the max( grep hits were CSS in the embedded HTML template, not Go builtins. No toolchain directive present. Build passes at language level 1.22.

Nothing else touched. No tag pushed — release handled by orchestrator.