chore(release): stamp v0.51.20 — 5-PR follow-on batch + 2 in-stage absorbs

5 contributor PRs across Kanban (#1828: stale-client recovery + hard-refresh
button + board-pointer drift fix), providers (#1827: Codex card live+cache
merge enhancing v0.51.19 #1812), cron (#1826: no-agent edits without prompt),
and workspace UI (#1825: cruft filter; #1822: heading root actions).

In-stage absorbs:
- static/panels.js: removed duplicate loadKanbanBoards tail call to avoid
  doubling /api/kanban/boards traffic under SSE-driven refreshes.
- tests/test_issue1807_codex_provider_card_live_models.py: CODEX_HOME
  isolation for v0.51.19 tests now load-bearing under PR #1827's cache merge.

Parallel-discovery resolution: #1821 (ai-ag2026, leaner) closed as
superseded by #1826 (Michaelyklam, more thorough — Mode badge,
disabled-prompt, i18n hint, screenshot).

4790 → 4805 collected (+15). 4794 pass + 8 skip + 1 xfail + 2 xpass.
Browser API harness 11/11 green. JS syntax 3/3 clean.
Opus advisor SHIP verdict, 1 absorbed in-release, 4 deferred to follow-ups.

Closes #1786, #1793, #1820, #1823.

ROADMAP.md

@@ -2,7 +2,7 @@
 
 > Web companion to the Hermes Agent CLI. Same workflows, browser-native.
 >
-> Last updated: v0.51.19 (May 7, 2026) — 4790 tests collected — 15-PR contributor sweep (workspace-prefix triple, file-picker + IPv6 + bootstrap pair, named custom provider routing, quota cards, session ownership, sidebar continuation)
+> Last updated: v0.51.20 (May 7, 2026) — 4805 tests collected — 5-PR contributor follow-on (Kanban stale-client recovery, Codex provider card live+cache merge, no-agent cron edits, workspace cruft filter + heading actions)
 > Test source: `pytest tests/ --collect-only -q`
 > Per-version detail: see [CHANGELOG.md](./CHANGELOG.md)