Add migration options: copy, symlink, or use in-place

When source is on mounted drive (/mnt/*, ~/drives/*, /media/*):
- [C] Copy - Copy to ~/docker (for old OS drive migration)
- [S] Symlink - Create ~/docker → source (for data drive)
- [U] Use in-place - Use source directly, no copy

This handles both scenarios:
- Old OS drive mounted temporarily → Copy
- Data drive you'll keep using → Symlink or use in-place

ubuntu-post-install.sh

@@ -720,9 +720,92 @@ run_migration() {
         echo ""
     fi
 
-    # Step 5: Copy containers
+    # Step 5: Decide migration method
-    echo "Step 5: Migrating containers"
+    echo "Step 5: Migration method"
-    echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+    echo "━━━━━━━━━━━━━━━━━━━━━━━━━"
+    echo ""
+
+    # Check if source is on a different drive (mounted drive, not home on OS)
+    SOURCE_ON_EXTERNAL=false
+    if [[ "$SOURCE_DOCKER_DIR" == /mnt/* ]] || [[ "$SOURCE_DOCKER_DIR" == /media/* ]] || [[ "$SOURCE_DOCKER_DIR" == */drives/* ]]; then
+        SOURCE_ON_EXTERNAL=true
+    fi
+
+    MIGRATION_METHOD="copy"
+    if [ "$SOURCE_ON_EXTERNAL" = true ]; then
+        echo "Source is on a mounted drive: $SOURCE_DOCKER_DIR"
+        echo ""
+        echo "How would you like to migrate?"
+        echo ""
+        echo "  [C] Copy - Copy containers to ~/docker on OS drive"
+        echo "             Best for: old OS drive mounted temporarily"
+        echo ""
+        echo "  [S] Symlink - Create ~/docker as symlink to source location"
+        echo "                Best for: data drive you'll keep using"
+        echo ""
+        echo "  [U] Use in-place - Use source location directly, no copy"
+        echo "                     Best for: already on your data drive"
+        echo ""
+        read -p "Method (C/S/U) [C]: " MIGRATION_METHOD
+
+        case "${MIGRATION_METHOD^^}" in
+            S)
+                MIGRATION_METHOD="symlink"
+                ;;
+            U)
+                MIGRATION_METHOD="use"
+                ;;
+            *)
+                MIGRATION_METHOD="copy"
+                ;;
+        esac
+    else
+        echo "Source: $SOURCE_DOCKER_DIR"
+        echo "Target: $DOCKER_DIR"
+        echo ""
+        echo "Will copy containers to $DOCKER_DIR"
+    fi
+
+    echo ""
+
+    # Handle different migration methods
+    case "$MIGRATION_METHOD" in
+        symlink)
+            echo "Creating symlink: $DOCKER_DIR → $SOURCE_DOCKER_DIR"
+            echo ""
+
+            # Check if target exists
+            if [ -e "$DOCKER_DIR" ] || [ -L "$DOCKER_DIR" ]; then
+                echo "  ⚠ $DOCKER_DIR already exists"
+                read -p "  Remove and create symlink? (y/n) [n]: " REMOVE_EXISTING
+                if [ "$REMOVE_EXISTING" = "y" ] || [ "$REMOVE_EXISTING" = "Y" ]; then
+                    rm -rf "$DOCKER_DIR"
+                else
+                    echo "  Cancelled."
+                    return 1
+                fi
+            fi
+
+            ln -s "$SOURCE_DOCKER_DIR" "$DOCKER_DIR"
+            chown -h "$ACTUAL_USER:$ACTUAL_USER" "$DOCKER_DIR"
+
+            echo "✓ Symlink created"
+            echo "  Containers stay at: $SOURCE_DOCKER_DIR"
+            echo "  Accessible via: $DOCKER_DIR → $SOURCE_DOCKER_DIR"
+            MIGRATED_COUNT=${#SELECTED_CONTAINERS[@]}
+            ;;
+
+        use)
+            echo "Using source location directly"
+            echo ""
+            DOCKER_DIR="$SOURCE_DOCKER_DIR"
+            echo "✓ DOCKER_DIR set to: $DOCKER_DIR"
+            echo "  No files copied - containers remain in place"
+            MIGRATED_COUNT=${#SELECTED_CONTAINERS[@]}
+            ;;
+
+        copy|*)
+            echo "Copying containers to $DOCKER_DIR"
             echo ""
 
             # Create target directory
@@ -751,13 +834,15 @@ run_migration() {
                         cp -a "$source_dir" "$target_dir"
                         chown -R "$ACTUAL_USER:$ACTUAL_USER" "$target_dir"
                         ((MIGRATED_COUNT++))
-                echo "    ✓ $container migrated"
+                        echo "    ✓ $container copied"
                     fi
                 done
             done
+            ;;
+    esac
 
     echo ""
-    echo "✓ Migrated $MIGRATED_COUNT container(s) to $DOCKER_DIR"
+    echo "✓ Migrated $MIGRATED_COUNT container(s)"
     echo ""
 
     # Step 6: Start migrated containers (optional)