feat(web): published-versions sidebar on the composer page

The lab redesign gave only the lab tab the published-history sidebar;
the composer page was expected to have it too. /setup/tariff now lists
every published version (name or effective date, active badge, currency)
on the right; clicking one loads it into the editor as the SEED for the
next publish — which always creates a new immutable version (the sidebar
hint states this), making "roll back to last month's prices" a two-click
republish while the history stays append-only.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

wiki/concepts/tariff.md

@@ -193,7 +193,11 @@ The admin authors the rate card at runtime — no hand-seeding:
   composer accumulates per-band hours into the engine's cumulative `uptoMin` (minutes) on submit. The
   **last band is always the open-ended "thereafter"** row (not removable, no hours field), so a
   published card always satisfies the open-ended-last rule. Shows the active version + history;
-  "Publish" creates a new version (past sessions keep their pricing).
+  "Publish" creates a new version (past sessions keep their pricing). Since 2026-07-05 a **right
+  sidebar lists the published history** (name or effective date, active badge — mirrors the lab's
+  sidebar); clicking a version **loads it into the editor as the starting point** for the next
+  publish (currency select ALL/EUR/USD; optional version-name field). Publishing never edits the
+  clicked version — the sidebar hint says so explicitly.
 - Ships **blank** — until a version is published, `GET /api/tariff` returns `active: null` and the
   pay station returns `409 no active tariff`. Verified end to end (publish → pay station prices).