- Custom color selection works again. Reverted the binding-gate
  (`state.color?.isCustom == true`) and the `selectCustomColor`
  entry action that the previous round added — that combination
  blocked the very first ColorPicker drag from promoting to
  `.custom`. Trade-off: a deliberate drag in the panel demotes
  `.red` to its sRGB-quantized hex, which is correct intent
  capture.
- System color panel no longer outlives the customization sheet.
  `RepositoryCustomizationView.onDisappear` calls
  `NSColorPanel.shared.orderOut(nil)`. Combined with the main
  Window's new `.restorationBehavior(.disabled)`, the panel can't
  be resurrected at next launch via state restoration.
- Force-quit-with-panel-visible now lands on the main window.
  `mainWindow(from:)`'s fallback filters `NSPanel` instances so
  `makeKeyAndOrderFront` can't surface a restored color panel as
  the "main window".
- Alt-tab no longer kills the in-progress color panel.
  `applicationDidBecomeActive` previously called
  `NSColorPanel.shared.orderOut(nil)` unconditionally, dismissing
  the user's panel mid-edit on every cmd-tab return. Removed
  alongside the launch-time orderOut now that
  `.restorationBehavior(.disabled)` handles resurrection at the
  source.
- Explicit `Remove Repository` no longer leaves a customization
  tombstone. `.repositoriesRemoved` purges
  `state.sidebar.sections[id]` before reconcile fires, so re-adding
  the same path doesn't silently restore the old title / color.
  `preserveOrphanSections` still keeps customization across
  transient drops (filesystem flutter).
- Dropped `RepositoryColor.hexString` (zero callers; the doc
  comment described a path that doesn't exist) and updated
  `displayName`'s docstring to reflect actual usage.
- Added a `RepositoriesFeatureCustomizationTests` regression
  asserting that explicit removal purges the sidebar tombstone.

- Set `NSColorPanel.shared.isRestorable = false` in
  `applicationDidFinishLaunching` so AppKit stops persisting the
  panel's visibility across launches. Reverted the main `Window`
  scene's `.restorationBehavior(.disabled)` — the main window
  stays restorable, only the system color panel opts out.
- Dropped the launch-time `NSColorPanel.shared.orderOut(nil)`;
  `isRestorable = false` alone handles forward sessions.
- Added a regression test pinning the predefined→custom demote
  on user-driven ColorPicker drags so a future refactor can't
  silently re-add the binding gate that broke first-drag.