feat(ui): shortcuts help panel — ?/Shift+/ toggle, Esc close, view+theme context (v1.19 E)

[argszero]

Summary

UI/UE 4th-round deepening — item E: shortcuts help panel (rant 2026-08-17T20:39:30, v1.19).

Pressing ? (or Shift+/) toggles a right-top inline card (#help-panel) — non-modal, no backdrop, doesn't block the page — showing a shortcut cheat-sheet:

• 4 shortcuts listed: / focus market search, 1–7 switch sidebar views, Esc close/cancel, ? toggle help
• Esc or pressing ? again closes; a × close button too
• Bottom context line: current view + light/dark theme (re-rendered on each open)
• Priority: when help is open, Esc closes help first (doesn't accidentally close an open "New Key" inline form); ? sits after the typing guard so it never hijacks input in fields
• Narrow screens (≤560px): full-width card pinned near top
• Styled .kbd keycaps consistent with the existing .nav-key visual language

Docs: docs/user-stories.md v1.19 (item E) + ui/README.md「快捷键帮助面板约定」. Verified by DOM-stub smoke test (21 assertions: open/close via ?, Esc, ×; content rows; typing guard; Esc priority over inline form; context updates on view switch; HTML/CSS structure), cargo test, cargo fmt --check.

Rant (verbatim)

Rant: UI/UE 第四轮多角度深化 — 状态保持、信息密度、原生控件美化、帮助可达性（宿主 2026-08-17 第四轮指示：继续从多角度美化 UI、优化 UE）

E. 快捷键帮助面板（? 键）

• 按 ?（或 Shift+/）弹出快捷键速查（行内卡片，非 modal）：列出 / 搜索、1-7 切视图、Esc 取消、? 帮助
• 按 Esc 或再次按 ? 关闭；显示当前主题/视图上下文相关提示

Related

• Rant timestamp: 2026-08-17T20:39:30.507364 (project aitokenpool, status in_progress; A = feat(ui): URL hash routing — share/bookmark/refresh restore (v1.19 A) #55, B = feat(ui): transactions summary bar — income/expense/net tied to tab & column filters (v1.19 B) #56, C = feat(ui): custom SVG select arrow — appearance:none, themed, hover/focus like input (v1.19 C) #57, D = feat(ui): toast queue — stack up to 3, independent fade in/out, keep grading styles (v1.19 D) #58 merged)
• Branch: feat/ui-ue-round4-help-panel (per rant: 分支 feat/ui-ue-round4; items F–G to follow)

Tests

• DOM-stub smoke test — 21/21 assertions pass
• node --check ui/js/app.js
• cargo test — 1 passed
• cargo fmt --check