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/daemon_lock_wasm.go

@@ -0,0 +1,14 @@
+//go:build js && wasm
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func flockExclusive(f *os.File) error {
+	// WASM doesn't support file locking
+	// In a WASM environment, we're typically single-process anyway
+	return fmt.Errorf("file locking not supported in WASM")
+}