feat(parcel-sync): DXF export in ZIP + detailed tooltips on hero buttons

DXF Export:
- Add gpkgToDxf() helper using ogr2ogr -f DXF (non-fatal fallback)
- export-local: terenuri.dxf, cladiri.dxf, terenuri_magic.dxf in ZIP
- export-bundle: same DXF files alongside GPKGs
- Zero overhead — conversion runs locally from DB data, no eTerra calls

Hero Button Tooltips:
- Hover shows ZIP contents: layer names, entity counts, sync dates
- Base tooltip: "GPKG + DXF per layer"
- Magic tooltip: "GPKG + DXF + CSV complet + Raport calitate"

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/modules/parcel-sync/services/gpkg-export.ts

@@ -175,3 +175,33 @@ export const buildGpkg = async (options: GpkgBuildOptions): Promise<Buffer> => {
   await fs.rm(tmpDir, { recursive: true, force: true });
   return buffer;
 };
+
+/**
+ * Convert a GPKG buffer to DXF using ogr2ogr.
+ * Returns null if ogr2ogr is not available or conversion fails.
+ */
+export const gpkgToDxf = async (
+  gpkgBuffer: Buffer,
+  layerName: string,
+): Promise<Buffer | null> => {
+  if (!hasOgr2Ogr()) return null;
+
+  const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "eterra-dxf-"));
+  const gpkgPath = path.join(tmpDir, "input.gpkg");
+  const dxfPath = path.join(tmpDir, `${layerName}.dxf`);
+
+  try {
+    await fs.writeFile(gpkgPath, gpkgBuffer);
+    await runOgr(
+      ["-f", "DXF", dxfPath, gpkgPath, layerName],
+      { ...process.env, OGR_CT_FORCE_TRADITIONAL_GIS_ORDER: "YES" },
+    );
+    const buffer = Buffer.from(await fs.readFile(dxfPath));
+    return buffer;
+  } catch {
+    // DXF conversion failed — not critical
+    return null;
+  } finally {
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  }
+};