fix: Windows-safe DB_PATH via env var, add Windows installer scripts

backend/batchtube-windows.spec

@@ -0,0 +1,54 @@
+# batchtube-windows.spec
+# PyInstaller spec for Windows single-file EXE
+# Run from backend/ directory: pyinstaller batchtube-windows.spec --clean
+# Output: dist/BatchTube.exe
+
+from PyInstaller.utils.hooks import collect_all
+block_cipher = None
+datas, binaries, hiddenimports = [], [], []
+for pkg in ['yt_dlp','uvicorn','fastapi','starlette','anyio','sse_starlette','youtube_transcript_api','openai','pydantic']:
+    d,b,h = collect_all(pkg)
+    datas+=d; binaries+=b; hiddenimports+=h
+datas += [('web','backend/web')]
+hiddenimports += [
+    'uvicorn.logging','uvicorn.loops','uvicorn.loops.auto','uvicorn.loops.asyncio',
+    'uvicorn.protocols','uvicorn.protocols.http','uvicorn.protocols.http.auto',
+    'uvicorn.protocols.http.h11_impl','uvicorn.protocols.http.httptools_impl',
+    'uvicorn.protocols.websockets','uvicorn.protocols.websockets.auto',
+    'uvicorn.lifespan','uvicorn.lifespan.off','uvicorn.lifespan.on',
+    'fastapi','fastapi.middleware.cors','starlette.middleware.cors',
+    'sse_starlette','sse_starlette.sse',
+    'pydantic','pydantic.v1','pydantic_core','annotated_types','typing_extensions',
+    'h11','httptools','httpx','anyio','anyio._backends._asyncio','sniffio',
+    'multipart','python_multipart','aiofiles','aiofiles.os','aiofiles.threadpool',
+    'yt_dlp','yt_dlp.extractor','yt_dlp.downloader','yt_dlp.postprocessor',
+    'youtube_transcript_api','youtube_transcript_api._transcripts',
+    'openai','openai.resources',
+    'requests','urllib3','certifi','charset_normalizer',
+    'slugify','python_slugify','tqdm','tqdm.auto',
+    'sqlite3','_sqlite3','asyncio','concurrent.futures','threading','queue',
+    'websockets','click','rich','watchfiles','mcp',
+    'api_server','worker','database','extractors','config',
+]
+a = Analysis(
+    ['batchtube-launcher.py'],
+    pathex=['.'],
+    binaries=binaries,
+    datas=datas,
+    hiddenimports=hiddenimports,
+    hookspath=[],
+    runtime_hooks=[],
+    excludes=['tkinter','matplotlib','numpy','pandas','torch','tensorflow','PyQt5','PyQt6'],
+    cipher=block_cipher,
+    noarchive=False,
+)
+pyz = PYZ(a.pure, a.zipped_data, cipher=block_cipher)
+exe = EXE(
+    pyz, a.scripts, a.binaries, a.zipfiles, a.datas, [],
+    name='BatchTube',
+    debug=False, strip=False, upx=True,
+    runtime_tmpdir=None,
+    console=False,
+    icon='../src-tauri/icons/icon.ico',
+    version='version_info.txt',
+)