Fix native Windows synchronized cursor placement

[Jinwoo-H]

Summary

• recognize native Windows synchronized-output frames whose final cursor show is followed by a cursor placement before the end marker
• rewrite that protected cursor tail so the cursor is placed before it is shown, avoiding an intermediate paint at the prior cell
• add a scheduler regression that fails when this frame waits for the fallback or writes show-before-place bytes

Validation

• pnpm exec vitest run --config config/vitest.config.ts src/renderer/src/lib/pane-manager/pane-terminal-output-scheduler.test.ts
• pnpm exec vitest run --config config/vitest.config.ts src/renderer/src/lib/pane-manager/pane-terminal-output-scheduler.test.ts src/renderer/src/components/terminal-pane/pty-connection.test.ts
• pnpm exec oxlint src/renderer/src/lib/pane-manager/pane-terminal-output-scheduler.ts src/renderer/src/lib/pane-manager/pane-terminal-output-scheduler.test.ts --quiet
• pnpm run typecheck:web
• pnpm run build:electron-vite
• pnpm run test:e2e:terminal-perf

Notes

• Tried to produce a fresh unpacked Windows package, but electron-builder hit local Windows file-lock/time-out issues before producing Orca.exe; no packaged validation is claimed from that attempt.

[pullfrog]

✅ No new issues found.

Reviewed changes — rewrites the cursor-show/cursor-position tail of synchronized-output frames on native Windows so the cursor is placed before it is shown, eliminating a flicker at the old cell.

• findCursorPositionSequenceEnd — extracts the end index of the next CUP / CHA / HVP escape (H, G, f) after a given offset, matching the existing cursor-position-recognition pattern in containsCursorPositionSequence.
• Rewrite in removeTransientCursorShowSequences — when a cursor-show has no subsequent hide but is followed by a cursor-position before data end, the position is sliced before the show. The comment captures the "why" cleanly.
• containsFinalCursorPlacementBeforeSynchronizedEnd — within a synchronized frame, detects whether the final show is followed by a position before the end marker. Feeds into coalescedQueuedDataNeedsCursorRestore to skip the fallback cursor-restore pass when the inline rewrite already handles it.
• Regression test — covers the show → position → sync-end pattern; asserts a single drain call (no fallback wait) and the reordered bytes.

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