refactor(document): move document domain core to document/ package

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/flatten-paperless.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+set -euo pipefail
+
+# ── Config ────────────────────────────────────────────────────────────────────
+INPUT_DIR="./paperless-download"
+OUTPUT_DIR="./paperless-flat"
+# ─────────────────────────────────────────────────────────────────────────────
+
+mkdir -p "$OUTPUT_DIR"
+
+MOVED=0
+SKIPPED=0
+
+while IFS= read -r -d '' FILE; do
+  BASENAME=$(basename "$FILE")
+
+  # Strip leading date prefix: "YYYY-MM-DD " → ""
+  NEWNAME=$(echo "$BASENAME" | sed -E 's/^[0-9]{4}-[0-9]{2}-[0-9]{2} //')
+
+  DEST="$OUTPUT_DIR/$NEWNAME"
+
+  if [ -e "$DEST" ]; then
+    echo "Skipping (already exists): $NEWNAME" >&2
+    SKIPPED=$((SKIPPED + 1))
+    continue
+  fi
+
+  cp "$FILE" "$DEST"
+  MOVED=$((MOVED + 1))
+done < <(find "$INPUT_DIR" -mindepth 2 -name "*.pdf" -print0)
+
+echo "Done. Copied $MOVED files to $OUTPUT_DIR/ ($SKIPPED skipped as duplicates)."