Implement local SQLite index database with repositories

- Add SQLite database connection management with proper error handling
- Implement schema for files, chunks, blobs, and snapshots tables
- Create repository pattern for each database table
- Add transaction support with proper rollback handling
- Integrate database module with fx dependency injection
- Make index path configurable via VAULTIK_INDEX_PATH env var
- Add fatal error handling for database integrity issues
- Update DESIGN.md to clarify file_chunks vs chunk_files distinction
- Remove FinalHash from BlobInfo (blobs are content-addressable)
- Add file metadata support (mtime, ctime, mode, uid, gid, symlinks)

internal/cli/app.go

@@ -0,0 +1,56 @@
+package cli
+
+import (
+	"context"
+	"fmt"
+
+	"git.eeqj.de/sneak/vaultik/internal/config"
+	"git.eeqj.de/sneak/vaultik/internal/database"
+	"git.eeqj.de/sneak/vaultik/internal/globals"
+	"go.uber.org/fx"
+)
+
+// AppOptions contains common options for creating the fx application
+type AppOptions struct {
+	ConfigPath string
+	Modules    []fx.Option
+	Invokes    []fx.Option
+}
+
+// NewApp creates a new fx application with common modules
+func NewApp(opts AppOptions) *fx.App {
+	baseModules := []fx.Option{
+		fx.Supply(config.ConfigPath(opts.ConfigPath)),
+		fx.Provide(globals.New),
+		config.Module,
+		database.Module,
+		fx.NopLogger,
+	}
+
+	allOptions := append(baseModules, opts.Modules...)
+	allOptions = append(allOptions, opts.Invokes...)
+
+	return fx.New(allOptions...)
+}
+
+// RunApp starts and stops the fx application within the given context
+func RunApp(ctx context.Context, app *fx.App) error {
+	if err := app.Start(ctx); err != nil {
+		return fmt.Errorf("failed to start app: %w", err)
+	}
+	defer func() {
+		if err := app.Stop(ctx); err != nil {
+			fmt.Printf("error stopping app: %v\n", err)
+		}
+	}()
+
+	// Wait for context cancellation
+	<-ctx.Done()
+	return nil
+}
+
+// RunWithApp is a helper that creates and runs an fx app with the given options
+func RunWithApp(ctx context.Context, opts AppOptions) error {
+	app := NewApp(opts)
+	return RunApp(ctx, app)
+}