ui/phase-18: ship-class calc bridge with live designer preview

Wires pkg/calc/ship.go into the WASM Core boundary as seven thin
wrappers (DriveEffective, EmptyMass, WeaponsBlockMass, FullMass,
Speed, CargoCapacity, CarryingMass). The ship-class designer reads
Core through a new CORE_CONTEXT_KEY populated by the in-game layout
and renders a five-row preview pane (mass, full-load mass, max
speed, range at full load, cargo capacity) that updates reactively
on every form edit and on the player's localPlayer{Drive,Weapons,
Shields,Cargo} tech levels — three of which are now decoded from
the report's Player block alongside the existing localPlayerDrive.

CarryingMass is the seventh wrapper added to the original six-function
list so that "full-load mass" composes through pkg/calc/ functions
without putting math in TypeScript.

ui/frontend/tests/galaxy-client.test.ts

@@ -208,5 +208,14 @@ function mockCore(opts: MockCoreOptions): Core & {
 		verifyResponse: vi.fn(opts.verifyResponseImpl),
 		verifyEvent: vi.fn(() => true),
 		verifyPayloadHash: vi.fn(opts.verifyPayloadHashImpl),
+		// `GalaxyClient` does not exercise the Phase 18 calc bridge,
+		// so these stubs only need to satisfy the `Core` interface.
+		driveEffective: () => 0,
+		emptyMass: () => 0,
+		weaponsBlockMass: () => 0,
+		fullMass: () => 0,
+		speed: () => 0,
+		cargoCapacity: () => 0,
+		carryingMass: () => 0,
 	};
 }