refactor(web): migrate from Next.js to Vite + React Router (#2102)

* refactor(web): migrate from Next.js to Vite + React Router

* fix: update build pipelines for Vite migration (out → dist)

- Dockerfile: npm run build → npx vite build, web/out → web/dist
- pyproject.toml: package-data web/out/** → web/dist/**
- paths.py: support both web/dist (Vite) and web/out (legacy) with fallback

* fix: remove .next from git tracking, add to .gitignore

1334 cached files from web/.next/ were accidentally committed.
Added .next/ to both root and web/.gitignore.

* fix: update build process to use Vite and correct output directory

* fix: update pnpm-lock.yaml and eslint config for Vite migration

* style: fix prettier formatting issues

* fix: add eslint-plugin-react-hooks for Vite migration

* fix: remove undefined eslint rule reference, downgrade react-hooks plugin to v5

* fix(web): clean up remaining Next.js artifacts in Vite migration

- Add vite-env.d.ts for import.meta.env and asset type declarations
- Remove dead layout.tsx (providers already in main.tsx)
- Fix useSearchParams destructuring to [searchParams] tuple (11 locations)
- Replace process.env.NEXT_PUBLIC_* with import.meta.env.VITE_*
- Fix langbotIcon.src to langbotIcon (Vite returns URL string)
- Fix Link href to Link to for react-router-dom
- Fix navigate({ scroll: false }) to { preventScrollReset: true }
- Fix [router] dependency arrays to [navigate]
- Remove Next.js plugin from tsconfig, set rsc: false in components.json
- Replace next lint with eslint in lint-staged

* feat: add tools API endpoint and tools-selector form type

Backend:
- Add GET /api/v1/tools — list all available tools (plugin + MCP)
- Add GET /api/v1/tools/<tool_name> — get specific tool details

Frontend:
- Add TOOLS_SELECTOR form type for plugin config forms
- Multi-select dialog with tool name and description
- Add PluginTool entity type and API client methods

* Revert "feat: add tools API endpoint and tools-selector form type"

This reverts commit 3c637fc563.

src/langbot/pkg/utils/paths.py

@@ -38,28 +38,31 @@ def get_frontend_path() -> str:
     """
     Get the path to the frontend build files.
 
-    Returns the path to web/out directory, handling both:
+    Returns the path to web/dist directory (Vite build output), handling both:
     - Development mode: running from source directory
     - Package mode: installed via pip/uvx
+    - Legacy mode: web/out (Next.js, for backward compatibility)
     """
-    # First, check if we're running from source directory
-    if _check_if_source_install() and os.path.exists('web/out'):
-        return 'web/out'
+    # Check both dist (Vite) and out (legacy Next.js) paths
+    for dirname in ('dist', 'out'):
+        web_dir = f'web/{dirname}'
 
-    # Second, check current directory for web/out (in case user is in source dir)
-    if os.path.exists('web/out'):
-        return 'web/out'
+        # First, check if we're running from source directory
+        if _check_if_source_install() and os.path.exists(web_dir):
+            return web_dir
 
-    # Third, find it relative to the package installation
-    # Get the directory where this file is located
-    # paths.py is in pkg/utils/, so parent.parent goes up to pkg/, then parent again goes up to the package root
-    pkg_dir = Path(__file__).parent.parent.parent
-    frontend_path = pkg_dir / 'web' / 'out'
-    if frontend_path.exists():
-        return str(frontend_path)
+        # Second, check current directory
+        if os.path.exists(web_dir):
+            return web_dir
+
+        # Third, find it relative to the package installation
+        pkg_dir = Path(__file__).parent.parent.parent
+        frontend_path = pkg_dir / 'web' / dirname
+        if frontend_path.exists():
+            return str(frontend_path)
 
     # Return the default path (will be checked by caller)
-    return 'web/out'
+    return 'web/dist'
 
 
 def get_resource_path(resource: str) -> str: