feat: add source export script and clean up .DS_Store tracking

Add scripts/export_source.sh to export project source to dist-source/,
add .DS_Store and dist-source/ to .gitignore, remove tracked .DS_Store.

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

.gitignore

@@ -1,8 +1,10 @@
 __pycache__/
 *.pyc
+.DS_Store
 .venv/
 *.egg-info/
 dist/
 build/
 backups/
 scan/
+dist-source/

scripts/export_source.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Export project source code to dist-source/ directory.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
+DIST_DIR="$PROJECT_DIR/dist-source"
+
+rm -rf "$DIST_DIR"
+mkdir -p "$DIST_DIR"
+
+# Copy project source and config files
+cp "$PROJECT_DIR/pyproject.toml" "$DIST_DIR/"
+cp "$PROJECT_DIR/uv.lock" "$DIST_DIR/"
+cp "$PROJECT_DIR/README.md" "$DIST_DIR/"
+cp "$PROJECT_DIR/CLAUDE.md" "$DIST_DIR/" 2>/dev/null || true
+
+# Copy directories
+for dir in src scripts docs; do
+    if [ -d "$PROJECT_DIR/$dir" ]; then
+        cp -r "$PROJECT_DIR/$dir" "$DIST_DIR/"
+    fi
+done
+
+# Remove __pycache__ from exported source
+find "$DIST_DIR" -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true
+find "$DIST_DIR" -name ".DS_Store" -delete 2>/dev/null || true
+
+echo "Exported to $DIST_DIR/"