feat(bar): timezone line in the clock tooltip (LATER item)

Hovering the clock now leads with the zone — "{:%Z (UTC%z)}" above the
calendar — on the generated bar and both summer whole-swaps (parity).
Under auto-timezone the existing tz-watch SIGUSR2 reload keeps it
showing the currently detected zone. %Z is the abbreviation (BST), not
the IANA name — strftime has no code for that, and it satisfies the
"(optional)" nicety.

Verified: V0; V1 — the rendered generated config carries the new
tooltip-format and both summer jsonc parse with it. Hover render
queued for hardware.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent/HARDWARE-QUEUE.md

@@ -167,6 +167,10 @@ QA machine), the **T14s** (webcam case).
       (tooltips, fastfetch labels) is visible on summer-day +
       flexoki-light, kanagawa floats are lighter than the bg (upstream
       sumiInk4). Anything that reads worse than before → reopen 28b.
+- [ ] **Clock zone tooltip (LATER item)** — hover the bar clock: the
+      tooltip's first line shows the zone ("BST (UTC+0100)") above the
+      calendar, on the generated AND summer bars; with auto-timezone
+      on, a zone change updates it (the SIGUSR2 reload).
 - [ ] **Doctor bar tripwire (LATER item)** — with everything healthy
       the bar shows nothing; `systemctl --user start doomed`-style
       induced failure → within ~5 min a red  appears (tooltip lists