feat: throw to the next display, larger and smaller, and cycled halves

[ostapondo]

What changed, and why

Four things a Rectangle user reaches for that Plonk did not have, on Rectangle's keys:

• ⌃⌥⌘→ and ⌃⌥⌘← throw the front window to the next or previous display. If it was in a numbered zone and the other display's set has that number, it lands in that zone; otherwise it keeps its share of the screen.
• ⌃⌥= and ⌃⌥- grow and shrink the window by 30 points about its centre. A side against the screen edge stays there, so a left half grows to the right. A window filling the screen only shrinks.
• ⌃⌥← on a window already in the left half takes two thirds, then a third, then the half again. Same for the other three halves. Off with a switch under Keys on the Zones page.

All four answer to Rectangle's URL names (next-display, previous-display, larger, smaller) and come across with the Rectangle import. "throw it to the next screen" and "make it bigger" work by voice.

What you ran

(cd App && swift build)
./scripts/test.sh                 497 pass, 16 new
./scripts/lint.sh
node scripts/check-strings.mjs

Checks

• swift build passes on every commit in the branch
• New logic is covered: WindowSizingTests, PresetCycleTests, DisplayOrderTests, VoiceThrowResizeTests, and the URL names in URLCommandTests
• Conventional commits
• Nothing touches the network, permissions, entitlements or the update path
• No screenshots; the visible change is two new shortcut sections and a Keys card on the Zones page

If this moves windows

Setup: macOS 26, one built-in display at 2x.

• One screen. Driven through plonk://execute-action on a bench window: left-half three times gave w 0.5, 0.67, 0.33; center then larger grew it from w 0.6 to 0.62 and smaller brought it back; next-display on one screen moved nothing and said so; unsnap restored the original frame.
• Put it back. ⌃⌥0 after larger and after a cycle restores the frame from before the first move.
• Second monitor: no hardware. The throw is the case that needs it; DisplayOrderTests covers the left-to-right order.
• Mixed scale factors: no hardware.
• Unplug and plug back in: not touched.
• Excluded app: all four go through the same focused() check as the other shortcuts.

left-half x3
  plonk-bench-1.txt      screen 0  x 0.000  y 0.000  w 0.500  h 1.000
  plonk-bench-1.txt      screen 0  x 0.000  y 0.000  w 0.670  h 1.000
  plonk-bench-1.txt      screen 0  x 0.000  y 0.000  w 0.330  h 1.000
center, larger, smaller
  plonk-bench-1.txt      screen 0  x 0.200  y 0.150  w 0.600  h 0.700
  plonk-bench-1.txt      screen 0  x 0.190  y 0.140  w 0.620  h 0.730
  plonk-bench-1.txt      screen 0  x 0.200  y 0.150  w 0.600  h 0.700
unsnap
  plonk-bench-1.txt      screen 0  x 0.110  y 0.050  w 0.380  h 0.390