refactor: remove unused bd pin/unpin/hook commands (bd-x0zl)

Analysis found these commands are dead code:
- gt never calls `bd pin` - uses `bd update --status=pinned` instead
- Beads.Pin() wrapper exists but is never called
- bd hook functionality duplicated by gt mol status
- Code comment says "pinned field is cosmetic for bd hook visibility"

Removed:
- cmd/bd/pin.go
- cmd/bd/unpin.go
- cmd/bd/hook.go

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/doctor/sqlite_open.go

@@ -0,0 +1,54 @@
+package doctor
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+func sqliteConnString(path string, readOnly bool) string {
+	path = strings.TrimSpace(path)
+	if path == "" {
+		return ""
+	}
+
+	// Best-effort: honor the same env var viper uses (BD_LOCK_TIMEOUT).
+	busy := 30 * time.Second
+	if v := strings.TrimSpace(os.Getenv("BD_LOCK_TIMEOUT")); v != "" {
+		if d, err := time.ParseDuration(v); err == nil {
+			busy = d
+		}
+	}
+	busyMs := int64(busy / time.Millisecond)
+
+	// If it's already a URI, append pragmas if absent.
+	if strings.HasPrefix(path, "file:") {
+		conn := path
+		sep := "?"
+		if strings.Contains(conn, "?") {
+			sep = "&"
+		}
+		if readOnly && !strings.Contains(conn, "mode=") {
+			conn += sep + "mode=ro"
+			sep = "&"
+		}
+		if !strings.Contains(conn, "_pragma=busy_timeout") {
+			conn += fmt.Sprintf("%s_pragma=busy_timeout(%d)", sep, busyMs)
+			sep = "&"
+		}
+		if !strings.Contains(conn, "_pragma=foreign_keys") {
+			conn += sep + "_pragma=foreign_keys(ON)"
+			sep = "&"
+		}
+		if !strings.Contains(conn, "_time_format=") {
+			conn += sep + "_time_format=sqlite"
+		}
+		return conn
+	}
+
+	if readOnly {
+		return fmt.Sprintf("file:%s?mode=ro&_pragma=foreign_keys(ON)&_pragma=busy_timeout(%d)&_time_format=sqlite", path, busyMs)
+	}
+	return fmt.Sprintf("file:%s?_pragma=foreign_keys(ON)&_pragma=busy_timeout(%d)&_time_format=sqlite", path, busyMs)
+}