Keyboard shortcuts for map view: zoom (+/-) and Home (center active boat)

[rolker]

Part of #143.

Keyboard shortcuts for common view/navigation actions in the CAMP map, requested in
the #143 usability wishlist (item 3). Scope is deliberately limited to non-destructive
view actions; command/control shortcuts (hover, standby, manual/autonomous, abort) are
out of scope here and will be tracked separately with input guards, since binding
boat commands to bare keypresses on an autonomous vessel is a safety concern.

Shortcuts

• Zoom in — +, =, and numpad +
• Zoom out — - and numpad -
• Home — center the map on the active boat

Binding = (and numpad) alongside + avoids requiring Shift for zoom-in on US keyboards.

"Active boat" semantics

The active platform is whichever platform tab is selected in the Platform Manager —
the existing AutonomousVehicleProject::activePlatform() concept. With multiple platforms
tracked, the operator selects the active one by selecting its tab. This matches the
"active boat = selected tab" definition shared with the lat/lon readout in #148.

Implementation hooks (verified in source)

• Zoom: ProjectView::wheelEvent already zooms via scale(0.8,0.8) / scale(1.25,1.25).
  Reuse the same factors from key handling so keyboard and wheel zoom match. ProjectView
  has no keyPressEvent today.
• Center: ProjectView::centerMap(QGeoCoordinate) already centers on a geo position.
  The active platform's live position is available via MainWindow::activePlatformPosition
  (and activePlatform()). Home → fetch active platform position → centerMap(), with a
  no-op guard when there is no active platform (mirror the if(p) guard in sendHover/sendGoto).
• Registration: use application-level shortcuts (e.g. Qt::ApplicationShortcut) so
  zoom/Home work regardless of which panel currently has focus, not only when the map view
  is focused.

Out of scope (follow-ups)

• Continuous follow-vehicle mode (there is a commented-out follow_vehicle look-at hook)
  — a toggle distinct from one-shot Home centering.
• Command/control shortcuts (hover / standby / manual-autonomous / abort) with guards.
• User-remappable keymap (start with a fixed mapping; revisit if operators want remapping).

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Authored-By: Claude Code Agent
Model: Claude Opus 4.8 (1M context)