ui/phase-20: ship-group inspector actions

Eight ship-group operations land on the inspector behind a single
inline-form panel: split, send, load, unload, modernize, dismantle,
transfer, join fleet. Each action either appends a typed command to
the local order draft or surfaces a tooltip explaining the
disabled state. Partial-ship operations emit an implicit
breakShipGroup command before the targeted action so the engine
sees a clean (Break, Action) pair on the wire.

`pkg/calc.BlockUpgradeCost` migrates from
`game/internal/controller/ship_group_upgrade.go` so the calc
bridge can wrap a pure pkg/calc formula; the controller now
imports it. The bridge surfaces the function as
`core.blockUpgradeCost`, which the inspector calls once per ship
block to render the modernize cost preview.

`GameReport.otherRaces` is decoded from the report's player block
(non-extinct, ≠ self) and feeds the transfer-to-race picker. The
planet inspector's stationed-ship rows become clickable for own
groups so the actions panel is reachable from the standard click
flow (the renderer continues to hide on-planet groups).

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

ui/core/calc/ship.go

@@ -55,3 +55,13 @@ func CargoCapacity(cargo, cargoTech float64) float64 {
 func CarryingMass(load, cargoTech float64) float64 {
 	return calc.CarryingMass(load, cargoTech)
 }
+
+// BlockUpgradeCost wraps `calc.BlockUpgradeCost` (`pkg/calc/ship.go`):
+// production cost of upgrading a single ship block from currentBlockTech
+// to targetBlockTech. Returns 0 when blockMass is zero or the target is
+// not above the current level. Used by the ship-group inspector's
+// modernize cost preview, with each of the four blocks (drive, weapons,
+// shields, cargo) priced through a separate call.
+func BlockUpgradeCost(blockMass, currentBlockTech, targetBlockTech float64) float64 {
+	return calc.BlockUpgradeCost(blockMass, currentBlockTech, targetBlockTech)
+}

ui/core/calc/ship_test.go

@@ -171,6 +171,31 @@ func TestCarryingMassParity(t *testing.T) {
 	}
 }
 
+func TestBlockUpgradeCostParity(t *testing.T) {
+	t.Parallel()
+	cases := []struct {
+		name        string
+		blockMass   float64
+		currentTech float64
+		targetTech  float64
+	}{
+		{"zero_block_mass", 0, 1, 2},
+		{"target_equal_to_current", 5, 2, 2},
+		{"target_below_current", 5, 2, 1},
+		{"doubling_tech_on_mass_5", 5, 1, 2},
+		{"partial_step_2_to_2_5", 5, 2, 2.5},
+		{"high_tech_to_higher_tech", 12, 4, 6},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			t.Parallel()
+			want := source.BlockUpgradeCost(c.blockMass, c.currentTech, c.targetTech)
+			got := bridge.BlockUpgradeCost(c.blockMass, c.currentTech, c.targetTech)
+			assert.Equal(t, want, got)
+		})
+	}
+}
+
 // TestDesignerPreviewComposition exercises the exact composition the
 // ship-class designer performs: empty mass, full-load mass via
 // CarryingMass(CargoCapacity), max speed at empty, and range at full