feat: resource collection with E-key interaction (Phase 4.3)

Mineral veins yield metals (Fe, Cu, Zn, Au, Sn), geysers yield S/H.
Resources spawn as ECS entities with gold/orange dot sprites on tiles.
E-key collects nearest resource in range into inventory. Resources
deplete after collection. Visual feedback text. 12 new tests (174 total).

Co-authored-by: Cursor <cursoragent@cursor.com>

src/ecs/components.ts

@@ -39,3 +39,9 @@ export const ChemicalComposition = {
 export const PlayerTag = {
   _tag: [] as number[],
 };
+
+/** Harvestable resource — mineral veins, geysers, etc. */
+export const Resource = {
+  quantity: [] as number[],       // remaining items to collect
+  interactRange: [] as number[],  // max interaction distance in pixels
+};