Open secondary windows on the main window's screen (#59) (#135)

* Open secondary windows on the main window's screen (#59)

Every Compose window but the main one went to the platform's default
position, which on a multi-monitor desk is the primary screen - the
station map could open on a monitor that was switched off. They now open
centred on the screen the main window is on, with their size clamped to
that screen's usable area (insets considered). A window the operator
moved during the session reopens there, as long as its title bar can
still be grabbed on a connected screen; otherwise it falls back to the
main window's screen. The position lives only in the window's host and
is never persisted. ComposeAlert dialogs and the profile picker are
centred the same way once the main window exists.

The rule is a pure function (WindowPlacement) with 18 unit tests; the
AWT side (WindowPlacementOnScreen) only reads the screens and the main
window's bounds on the event thread. The clamped opening size of a
secondary window is not written back, so the stored size survives a
smaller screen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Track window moves reliably and keep remembered windows on screen (#59)

Review fixes for the window placement:

- Once a window has left the tolerance around its opening position,
  every later position is remembered. Before, the anchor was never
  re-set, so dragging away and back to near the opening spot left the
  stale far position remembered.
- A window the host did not place (opened before the main window
  exists) only trusts its anchor once two consecutive reports lie
  within the tolerance, so a provisional position followed by the
  window manager's placement jump is no longer taken as the operator's
  move.
- A remembered position is shifted the least distance that puts the
  (clamped) window wholly inside the usable area of the screen holding
  its title bar, as the KDoc promised.

The move rule moves into a pure MoveTracker with 5 tests; WindowPlacement
gains keptWithin and 2 more tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Keep window positions across restarts as an opt-in; fit windows to small screens (#59)

A new GUI tab option, off by default, keeps the position the operator last
moved each window to, the main window included. It is stored per window
with the bounds of the screen it was on, written by the layout autosave,
and restored only when a screen with exactly those bounds is connected
again; otherwise the session rule applies. Only operator moves are
stored, never window manager nudges, so a restored window cannot drift.

An open window that rests on a screen too small for it is now cut down
to that screen's usable area, and the station map's 900x600 minimum is
capped to the smallest connected screen, so 640x480 monitors stay usable.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Never store a size or position the host fitted a window to (#59)

The cut-down to a small screen was written back as the stored size
(main window via onResized, others via the tracker) and counted as an
operator move. The host now records its own fit: that size is not
written back, and that position re-anchors the move tracker instead of
being stored. A main window opened at a stored position skips its
opening size like the other windows, since it may be clamped too.
The opt-in gate moves into PreferencesWindowPositionMemory, with tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Match the fit echo with tolerance and consume it once (#59)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

docs/PROJECT_CONTEXT.md

@@ -64,6 +64,7 @@ A batch of changes belongs in one `SimpleRoster.mutate(...)`, not one call per e
 - Stored widths take precedence. Without a usable entry, a managed column is sized once when meaningful table data first becomes available. Message and similar free-text columns use a flexible initial width instead of following the longest value.
 - Main-window and separate-monitor DXCluster/QSO tables use distinct layout IDs even though they share the underlying message stores.
 - Window sizes and positions, relevant divider positions and managed column widths are selectively autosaved after a short debounce. A pending write is flushed during application shutdown.
+- Window positions are persisted only as an **opt-in** (`guiOptions_rememberWindowPositions`, GUI tab, off by default; issue #59). Every secondary window and every `ComposeAlert`/profile-picker dialog opens centred on the screen the main window is on (`WindowPlacement`, fed by `WindowPlacementOnScreen`). A window the operator moved during the running session reopens there (shifted wholly into that screen's usable area), held in its `ComposeWindowHost` and tracked by `MoveTracker`; the remembered spot is dropped in favour of the main window's screen when its title bar cannot be reached on any connected screen. With the opt-in, operator moves (never window-manager nudges) are also stored per window id (the host's thread name) as `windowPosition` elements with the screen bounds they were made on, written by the layout autosave; a stored position is restored only when a screen with exactly those bounds is connected (`WindowPlacement.restore`), for the main window too. Order for secondary windows: session move, then stored position, then main window's screen. Opening sizes are clamped to the target screen's usable area without writing the clamped size back; an open window that rests on a screen too small for it is cut down (`WindowPlacement.fitted`), and enforced minimum sizes are capped to the smallest connected screen. Without a stored position the main window keeps the platform's placement; before it exists (update window, profile picker at startup) the platform decides as before. `GUIstationMapStagePositionXY` is an unused JavaFX leftover and must not be revived for this.
 - Selective layout writes update the XML already on disk, preserve unknown XML nodes and must not persist unconfirmed functional settings from the current UI. **Save Settings** remains the full settings writer and includes the current layout.
 - Full and selective writes are synchronized and replace `preferences.xml` atomically. Missing, unknown or malformed width entries do not prevent loading and fall back to initial sizing.
 - Older configuration files require no migration. Older KST4Contest versions can ignore the additional elements; a complete rewrite by such a version may discard column widths without invalidating the remaining file.