WIP: WASM port - switch to ncruces/go-sqlite3, add WASM stubs

- Switched from modernc.org/sqlite to ncruces/go-sqlite3 for WASM support
- Added WASM-specific stubs for daemon process management
- Created wasm/ directory with build.sh and Node.js runner
- WASM build succeeds (32MB bd.wasm)
- Node.js can load and execute the WASM module
- Next: Need to bridge Go file I/O to Node.js fs module

Related: bd-44d0, bd-8534, bd-c7eb

cmd/bd/migrate.go

@@ -16,7 +16,8 @@ import (
 	"github.com/steveyegge/beads/internal/storage/sqlite"
 	"github.com/steveyegge/beads/internal/types"
 	"github.com/steveyegge/beads/internal/utils"
-	_ "modernc.org/sqlite"
+	_ "github.com/ncruces/go-sqlite3/driver"
+	_ "github.com/ncruces/go-sqlite3/embed"
 )
 
 var migrateCmd = &cobra.Command{