Merge wasm-port-bd-44d0: Add npm package with native binaries

Merges complete npm package implementation for @beads/bd.

Features:
- npm package wrapping native bd binaries
- Automatic platform-specific binary download
- Claude Code for Web integration via SessionStart hooks
- Comprehensive integration test suite (5 tests, all passing)
- Complete documentation (6 guides)
- Release process documentation

Published to npm: https://www.npmjs.com/package/@beads/bd

Benefits over WASM:
- Full SQLite support (native vs custom VFS)
- Better performance
- Simpler implementation and maintenance
- 100% feature parity with standalone bd

Closes bd-febc

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")
+}

cmd/bd/daemon_wasm.go

@@ -0,0 +1,28 @@
+//go:build js && wasm
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+// WASM doesn't support signals or process management
+var daemonSignals = []os.Signal{}
+
+func configureDaemonProcess(cmd *exec.Cmd) {
+	// No-op in WASM
+}
+
+func sendStopSignal(process *os.Process) error {
+	return fmt.Errorf("daemon operations not supported in WASM")
+}
+
+func isReloadSignal(sig os.Signal) bool {
+	return false
+}
+
+func isProcessRunning(pid int) bool {
+	return false
+}

cmd/bd/doctor.go

@@ -16,7 +16,8 @@ import (
 	"github.com/steveyegge/beads"
 	"github.com/steveyegge/beads/internal/configfile"
 	"github.com/steveyegge/beads/internal/daemon"
-	_ "modernc.org/sqlite"
+	_ "github.com/ncruces/go-sqlite3/driver"
+	_ "github.com/ncruces/go-sqlite3/embed"
 )
 
 // Status constants for doctor checks

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{