Clean repo for open source release

Remove build artifacts, dev tool configs, unused dependencies,
and third-party source dumps. Add proper README, update .gitignore,
clean up Makefile.

src/main/java/com/tiedup/remake/cells/FloodFillResult.java

@@ -0,0 +1,140 @@
+package com.tiedup.remake.cells;
+
+import java.util.*;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Immutable result container returned by the flood-fill algorithm.
+ *
+ * Either a success (with geometry and detected features) or a failure (with an error translation key).
+ */
+public class FloodFillResult {
+
+    private final boolean success;
+
+    @Nullable
+    private final String errorKey;
+
+    // Geometry
+    private final Set<BlockPos> interior;
+    private final Set<BlockPos> walls;
+
+    @Nullable
+    private final Direction interiorFace;
+
+    // Auto-detected features
+    private final List<BlockPos> beds;
+    private final List<BlockPos> petBeds;
+    private final List<BlockPos> anchors;
+    private final List<BlockPos> doors;
+    private final List<BlockPos> linkedRedstone;
+
+    private FloodFillResult(
+        boolean success,
+        @Nullable String errorKey,
+        Set<BlockPos> interior,
+        Set<BlockPos> walls,
+        @Nullable Direction interiorFace,
+        List<BlockPos> beds,
+        List<BlockPos> petBeds,
+        List<BlockPos> anchors,
+        List<BlockPos> doors,
+        List<BlockPos> linkedRedstone
+    ) {
+        this.success = success;
+        this.errorKey = errorKey;
+        this.interior = Collections.unmodifiableSet(interior);
+        this.walls = Collections.unmodifiableSet(walls);
+        this.interiorFace = interiorFace;
+        this.beds = Collections.unmodifiableList(beds);
+        this.petBeds = Collections.unmodifiableList(petBeds);
+        this.anchors = Collections.unmodifiableList(anchors);
+        this.doors = Collections.unmodifiableList(doors);
+        this.linkedRedstone = Collections.unmodifiableList(linkedRedstone);
+    }
+
+    public static FloodFillResult success(
+        Set<BlockPos> interior,
+        Set<BlockPos> walls,
+        Direction interiorFace,
+        List<BlockPos> beds,
+        List<BlockPos> petBeds,
+        List<BlockPos> anchors,
+        List<BlockPos> doors,
+        List<BlockPos> linkedRedstone
+    ) {
+        return new FloodFillResult(
+            true,
+            null,
+            interior,
+            walls,
+            interiorFace,
+            beds,
+            petBeds,
+            anchors,
+            doors,
+            linkedRedstone
+        );
+    }
+
+    public static FloodFillResult failure(String errorKey) {
+        return new FloodFillResult(
+            false,
+            errorKey,
+            Collections.emptySet(),
+            Collections.emptySet(),
+            null,
+            Collections.emptyList(),
+            Collections.emptyList(),
+            Collections.emptyList(),
+            Collections.emptyList(),
+            Collections.emptyList()
+        );
+    }
+
+    // --- Getters ---
+
+    public boolean isSuccess() {
+        return success;
+    }
+
+    @Nullable
+    public String getErrorKey() {
+        return errorKey;
+    }
+
+    public Set<BlockPos> getInterior() {
+        return interior;
+    }
+
+    public Set<BlockPos> getWalls() {
+        return walls;
+    }
+
+    @Nullable
+    public Direction getInteriorFace() {
+        return interiorFace;
+    }
+
+    public List<BlockPos> getBeds() {
+        return beds;
+    }
+
+    public List<BlockPos> getPetBeds() {
+        return petBeds;
+    }
+
+    public List<BlockPos> getAnchors() {
+        return anchors;
+    }
+
+    public List<BlockPos> getDoors() {
+        return doors;
+    }
+
+    public List<BlockPos> getLinkedRedstone() {
+        return linkedRedstone;
+    }
+}