Summary

Three new selection tools + two PS-alignment UX fixes.

Selection tools (Lasso, Polygonal Lasso, Magic Wand)

• Lasso (L) — drag to trace a freeform region; release to close. Path subsamples to ≥2 px between points so memory stays bounded on slow drags.
• Polygonal Lasso — click-by-click vertex chain with a rubber-band preview from the last vertex to the cursor. Click within 8 px of the first vertex (or hit Esc) to close. Vertex dots are orange (first) and white (rest) so it's obvious where you've clicked.
• Magic Wand (W) — reuses the Paint Bucket's scanline flood fill; stores the bbox of the matched region as a rectangular selection. Tolerance is exposed in the options bar (0–128, slider + number).

State changes

• New optional EditorState.selectionPath?: Point[] — when present, refines the selection outline from the bbox rect to a closed polygon. Rendered via a new drawSelectionPathChrome helper (black halo + white marching-ants dashes, identical look to the marquee but along an arbitrary path).
• serializeProject round-trips selectionPath so polygon selections survive .json save / reload.
• Cmd/Ctrl+D and the "Deselect" button now clear both selection and selectionPath (formerly only the rect). Marquee commit explicitly clears selectionPath so a stale polygon doesn't outline a fresh rectangular selection.

Canvas additions

• New interaction kinds: lasso-drawing, polylasso-drawing.
• CanvasHandle gains hasPendingPolyLasso and cancelPendingPolyLasso, mirroring the existing crop pair so Esc in the parent's keyboard handler cancels the pending vertex chain cleanly.

OptionsBar

• Marquee / Lasso / PolyLasso share one variant (hint + "Deselect" button when active).
• Wand gets its own variant: tolerance number + range slider, hint, "Deselect".
• Hand gets a hint variant.

UX fixes (bundled)

• F shortcut unbound — Photoshop's F cycles screen modes, not "toggle fullscreen UI"; freeing the key avoids the muscle-memory clash.
• Green Fullscreen button in the tab strip's right corner (turns red when active, indicating "click to exit"). Replaces the muted "⛶ F" tab.
• Hand tool (H) is no longer a stub — selecting it puts the editor into pan mode (same as holding Space). New effectivePanMode = panMode || tool === 'hand' is wired into both Workspace and Canvas.

i18n

New keys (en + zh-CN): lassoHint, polyLassoHint, wandHint, wandTolerance, wandEmpty, handHint. Updated focusEnterHint / focusExitHint to drop the F reference.

Test plan

• L: drag a freeform path, release — selection appears with marching-ants polygon outline. Survives undo/redo.
• PolyLasso: click vertices, click near the first vertex (or Esc) — polygon closes / cancels.
• W: click on a uniform region — bbox of matching pixels becomes the selection. Adjust tolerance, click again — bbox grows/shrinks.
• Marquee → Lasso → Marquee: switching tools doesn't leak a stale polygon outline.
• Save .json → reload — both rect and polygon selections round-trip.
• Cmd/Ctrl+D + Deselect button clear the selection regardless of source tool.
• Crop applied → selection with each new tool — coords align to the cropped image.
• H: cursor becomes grab; drag pans the canvas. Press F: nothing happens (unbound). Click green "⛶ Fullscreen" — UI hides; button turns red "⛶ Exit fullscreen". Click again or hit Esc to exit.

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