* fix(sync): replace cryptic sigil counters with readable output
Problem: sync summaries used unexplained sigils (`+/-/~` and `!`) that
conveyed no meaning, mixed symbol and prose formats across operations,
and `gcal push` silently swallowed failures with no aggregate counter.
Solution: replace all summary `log.info` calls with a shared
`fmt_counts` helper that formats `N label` pairs separated by ` | `,
suppresses zero counts, and falls back to "nothing to do". Add a
`failed` counter to `gcal.push` to surface errors previously only
emitted as individual warnings.
* ci: format
ff73164b61