feat(ui): F8-10 — tables planets / ship-groups / fleets, ship-classes delete guard (#53)

Lights up three previously-stubbed table active views and tightens the
existing one:

  - table-planets: 4 kind checkboxes (own / foreign / uninhabited /
    unknown) + race dropdown that filters the foreign slice; row click
    selects + centres the planet on the map.
  - table-ship-groups: local + foreign groups in one grid, owner
    checkboxes, planet dropdown (destination OR origin), class
    dropdown; on-planet click focuses the destination planet, in-space
    click focuses the ship group itself (camera follows interpolated
    position).
  - table-fleets: own fleets only with the shared planet dropdown;
    on-planet click focuses the planet, in-space click centres the
    camera on the interpolated fleet position without altering the
    selection (no fleet variant in Selected).
  - table-ship-classes: per-row Delete is disabled with a count tooltip
    while at least one local ship group references the class. The
    engine refuses the removal anyway; the UI pre-empts the surface.

Wires the click → map flow through a transient `SelectionStore.focus`
/ `focusPoint` channel that `map.svelte` consumes once on mount —
in-memory only, so an F5 does not re-centre.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/frontend/src/map/ship-groups.ts

@@ -293,8 +293,12 @@ export function shipGroupsToPrimitives(
  * — the planet inspector lists them instead. Returns null when either
  * the group is on-planet, or the origin / destination planets are
  * not visible to the local player.
+ *
+ * Exported so the active-view map can centre the camera on an
+ * in-space group when the F8-10 tables raise a `selection.focus`
+ * request for one.
  */
-function computeInSpacePosition(
+export function computeInSpacePosition(
 	group: ReportLocalShipGroup | ReportOtherShipGroup,
 	planetIndex: Map<number, ReportPlanet>,
 	mapWidth: number,