…up) (#1680)

#1667 added totalCompletionTokens to SessionMeta and wrote it after every
turn via patchSessionMeta, but the carryover plumbing in SessionStats
was incomplete:

- seedCarryover didn't read meta.totalCompletionTokens
- SessionStats had no _carryoverCompletion field
- the write call summed only this.turns (no carryover), and trimOldTurns
  dropped completion tokens into the void

Net effect: on every resume, the first turn's patchSessionMeta call
overwrote the previously-saved totalCompletionTokens with just the new
turn's tally — counter reset to ~0 across restarts. (Cost / cache hit /
miss don't have this problem because they each have proper carryover
plumbing.)

Currently zero user-visible impact since no UI reads the field yet, but
the data was already flowing through UsageStats in both dashboard and
desktop, so the next surface that exposes it would inherit the bug.

Fix mirrors the cacheHit/Miss pattern: new _carryoverCompletion field
seeded from meta, a cumulativeCompletionTokens getter, trimOldTurns
folds completion tokens into carryover like the other counters, and
loop.ts switches the write to use the new getter.

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

…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.