fix(ui): derive the live containers from the DOM, not from rosters

[argszero]

Summary

Two hand-written rosters in ui/js/app.js enumerated the "live" containers by id, and both omitted the admin models table #model-body — which was added later (PR #97) while the rosters date from PR #69/#79:

1. bindLiveRetry("<id>", fn) (13 entries, bound once at DOMContentLoaded) attached the load-error 重试 button of each container. #model-body was never registered, so renderAdminModels() rendered a 重试 button that did nothing when clicked. The smoking gun is the renderer itself: loadErrorHtml(emptyLabel, retryFn, retryLabel) declared a retryFn parameter and never used it — the renderer was always meant to hand its loader over, and the roster was the only thing wiring it up.
2. KBD_TABLE_IDS listed the tables reachable by ↑/↓/Enter. #model-body was absent, so its rows could not be activated (no .row-active) while all seven sibling tables could.

The fix removes both rosters instead of extending them — a roster that must be maintained by hand is the defect, not the one missing entry. Both containers are now derived from the DOM, so no future table can be forgotten:

	Before	After
retry wiring	bindLiveRetry(id, fn) ×13 + per-container addEventListener	setLiveError(container, html, loader) — the renderer hands over its loader; one-time container delegation (WeakMap/WeakSet) dispatches [data-live-retry]
kbd container	KBD_TABLE_IDS.indexOf(tb.id) >= 0	kbdTbodyOf(t) = t.closest("tbody"), via a single document-level click delegation

Runtime evidence (a jsdom probe booting the real index.html + the four scripts, only fetch stubbed so the admin endpoints 500):

check	pre-change	post-change
#dept-body retry re-requests (control)	5	5
#model-body retry re-requests (test)	0	5
#model-body second retry click	0	5
#dept-body row click activates (control)	true	true
#model-body row click activates (test)	false	true
raise-requests rows activate (declared side effect)	false	true
a run-time-injected table's rows activate (no roster can cover it)	false	true
verdict	DEFECT — 5/7 failed	OK — 7/7

Related Issue

None — the repository carries no open issues. Found by reconciling the two enumerated rosters against the tables that actually exist.

Changes

• ui/js/app.js
  • setLiveError(container, html, loader) replaces the deleted bindLiveRetry; the dead retryFn parameter is dropped from loadErrorHtml. All 12 loadErrorHtml/loadErrorRow call sites now pass their loader through it.
  • KBD_TABLE_IDS deleted; the keyboard container is derived from the event target (kbdTbodyOf = closest("tbody")) and the row/table click delegations are merged into a single document-level listener.
  • kbdRows/kbdContainerFrom treat a container that has been rebuilt (isConnected === false) as "no active table" instead of highlighting rows that are gone.
• ui/index.html — cache-bust js/app.js?v=20260913-2 → -3.
• ui/README.md — the keyboard-nav and degradation-pattern sections named both deleted rosters; they now describe the DOM-derived contract.
• 涉及配置/数据结构的改动已同步示例文件 — N/A: no config or data-structure change.

Declared side effect (a consequence of "every data table is navigable"): the JS-built raise-requests table now has keyboard row navigation. It was outside the old roster and passed null for the retry callback, so its degraded state had no 重试 button at all; it now reloads through loadAdmin().

Tests

• cargo test 全部通过 — 190 passed / 0 failed, i.e. unchanged from main (this change is JS + docs only; the count staying put is the evidence that no Rust behaviour moved).
• cargo fmt --check 通过
• cargo clippy --all-targets -- -D warnings 通过
• 新增/更新了单元测试 — N/A: ui/ carries no test harness in-repo (the probes live outside it), and the change's assertion is the jsdom A/B above: with the pre-change app.js the probe is red (5/7), with this branch it is green (7/7), and the #dept-body control passes in both legs.

Checklist

• 分支命名符合约定 — fix/ui-live-container-rosters
• Commit message 使用 Conventional Commits 格式 — fix(ui): derive the live containers from the DOM, not from rosters
• 单一职责，改动最小化 — one defect class (enumerated live containers), no opportunistic refactor; node --check ui/js/app.js clean.