…moved, persisted usage stats, plan dispatch gate

Headline themes:
- Desktop: bundle the CLI-hosted React dashboard, retire Tauri+Preact duplicate (#1418)
- Config: drop preset abstraction; flash/pro are direct model selections (#1657, #1630)
- Stats: persist cumulative usage to session meta + auto-restore on startup (#1667, #1680, #1643, #1628)
- Plans: editMode="plan" enforced at the ToolRegistry dispatch gate (#1681); step advance fix (#1629)
- Context: fold once at turn start, drop pre-flight + byte-ceiling (#1642, #1646); collapsible compacted card (#1649)
- Subagents: per-skill flash/pro override + Settings UI (#1632)
- Desktop polish: sidebar drag-resize (#1688), responsive collapse (#1585), copy/edit overlay + msg-history nav (#1645), Esc closes modal not turn (#1685), QQ tab isolation (#1672), DiffCard for edits (#1662), theme-aware highlighting (#1655), system events toggle (#1654/#1650), macOS TCC inheritance (#1614), dashboard.enabled (#1612)
- Dashboard polish: persistent session URL (#1586, #1589, #1599), theme-aware highlighting (#1664), IME confirm-enter guard (#1689), code-fence lang fix (#1677), vendor chunk split (#1587), markdown table h-scroll (#1562)
- TUI: Alt+S input stash/recall; static history isolated from input rerenders (#1635); legacy mouse drop (#1637, #1648); multi-edit gated in review (#1647)
- Diff: SplitDiff column border holds under CJK (#1686)
- MCP: workspace roots passed to servers (#1625); codeCommand honors mcpServers (#1603)
- Config plumbing: (baseUrl, apiKey) resolved as a tuple (#1658); stale model id self-heal (#1663)

See CHANGELOG for the full list.

Three stale-doc fixes:

- ARCHITECTURE.md §4.3 — replace removed /pro single-turn arming with the
  current /model flash|pro + settings.json model selection. Note the
  removal in 0.50.0 (#1657, #1630).
- ARCHITECTURE.md §4.4 — replace the never-existed FAILURE_ESCALATION_THRESHOLD
  counter with the actual <<<NEEDS_PRO>>> model self-report mechanism. No
  failure-counter; purely LLM-initiated, no-op on pro tier.
- benchmarks/real-world-cache/README.md — fix 10× pricing error in
  v4-flash cache-hit ($0.028 → $0.0028) and entirely wrong v4-pro pricing
  ($0.139/1.667/3.333 → $0.003625/0.435/0.87). Recalculated cost tables;
  headline 99.82% hit ratio unchanged, savings now correctly show ~97.7%
  (flash) / ~98.9% (pro).

Thanks @FriendsHL for catching this — the benchmark pricing in particular
is the public cache-first defense link, the old numbers would have been
embarrassing.

#1657 dropped the preset abstraction and exposed reasoning effort
directly, keeping `max` as a DeepSeek-only extension that users opt
into knowing standard OpenAI / vLLM / Azure reject it with 400. The
TUI still advertised `max` everywhere — `/effort` argsHint, slash-arg
picker, ModelPicker effort rows, /effort handler — even when the
active endpoint was a third-party host that can't accept it. Users
on those endpoints saw `max` in every suggestion and reported it as
a preset-era leftover (#1794).

Endpoint-aware filter: when `loop.client.baseUrl` is not api.deepseek.com,
drop `max` from the choices the TUI surfaces:
  - `/effort` argsHint and argCompleter (autocomplete + arg picker)
  - ModelPicker effort rows
  - /effort handler's accept list + status / usage message
  - new `effortUsageNoMax` i18n key (EN / zh-CN / de) so the error
    on bad input doesn't itself name `max` as an option

`max` stays available on DeepSeek endpoints — that's the design from
#1657, just no longer visible where it would 400.

Fixes #1794.

Co-authored-by: reasonix <reasonix@deepseek.com>