One progress bar style, and checkboxes on the panel edge

[maralcbr]

Summary

Progress bars look the same on every screen and move smoothly, and loose rows line up with the panels.

 ProgressTrack(fraction:)
-  height: 10 / 14 / 18 per call site
+  height: OmarchyTheme.progressHeight (8)
-  fill: linear 0.18 s steps
+  fill: easeOut 0.6 s, never thinner than a dot once started
-  unknown length: 32% block bouncing back and forth
-                  (Reduce Motion: frozen 32% fill, reads as stalled)
+  unknown length: SweepingHighlight, travels one way
+                  Reduce Motion: BreathingFill, whole bar pulses

 plan review
-  EncryptDiskToggle: Toggle label, 4 pt inset
-  acknowledgement: own HStack, 12 pt gap, 4 pt inset
+  CheckboxRow (shared): label gap 8, help text under the label,
+                        inset = Panel content inset (14)

 OnePageInstallerView
+  stage .id(stageKey): a new screen fades in (old one leaves at once)

stageKey groups phases that show the same screen (preparing/prepared, review/awaiting install), so replanning and the credential sheet keep their state.

Evidence

• Before: in the simulator, the encrypt checkbox sat 4 pt in from the panel with its help under the box, and the backup checkbox had a wider gap. With Reduce Motion on, "Checking the release signature…" showed a static 32% fill.
  After: both checkboxes sit on the panel content edge with the same gap; the unknown-length bar pulses across the full width; download and install bars share one height.
• swift build (debug and release), strict swift-format lint, swift test: 677 tests, 0 failures.
• The one-way sweep was not seen on screen (the test Mac runs Reduce Motion); the pulse and the static layout were.

Merge Danger

Door: two-way

View-only change; no session, engine or helper code touched.

Blast Radius: layout

Plan review and progress screens shift slightly; a stage's views reset only when the screen really changes.