fix(git,macos,runs): close the review findings on #22, #34 and #38

- validateRemoteUrl checks the literal scheme prefix git will receive and
  refuses %/backslash in the authority (WHATWG normalises https:/host and
  percent-escapes that git reads differently); route test for EBADURL.
- Parent-session scrub also drops AI_AGENT, and GIT_EDITOR when it is
  Claude Code's `true`.
- canonicalCwd resolves a not-yet-existing path through its deepest
  existing ancestor, so a symlinked parent still yields one lane.
- Note the clock-step ceiling on liveServers' boot-time filter.
- Docs/header wording: the Active runs count is lane-scoped.

scripts/plugin-bootstrap.js

@@ -424,6 +424,8 @@ function liveServers() {
     // An entry older than this boot is a leftover whose pid may now belong to
     // an unrelated process (macOS has no systemd to clean up after a reboot).
     // 60 s margin for clock skew; an unparseable startedAt is kept.
+    // ponytail: an NTP step larger than 60 s after boot misreads a live entry
+    // as stale; compare against a monotonic boot id if that ever bites.
     const bootedAt = Date.now() - os.uptime() * 1000 - 60_000;
     return servers.filter((s) => s && isPidAlive(s.pid) && !(Date.parse(s.startedAt) < bootedAt));
   } catch {