Fix: Ensure JSONL directory exists in findJSONLPath

Added os.MkdirAll(dbDir, 0755) to ensure the .beads directory exists
before attempting to glob for JSONL files. This fixes a bug where
findJSONLPath() would fail silently if the directory doesn't exist yet,
which can happen during new database initialization.

The fix:
- Creates the directory with 0755 permissions if it doesn't exist
- Handles errors gracefully by returning the default path
- Subsequent write operations will still fail with clear errors if
  directory creation fails

Closes bd-36

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

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

cmd/bd/main.go

@@ -202,6 +202,13 @@ func findJSONLPath() string {
 	// Get the directory containing the database
 	dbDir := filepath.Dir(dbPath)
 
+	// Ensure the directory exists (important for new databases)
+	if err := os.MkdirAll(dbDir, 0755); err != nil {
+		// If we can't create the directory, return default path anyway
+		// (the subsequent write will fail with a clearer error)
+		return filepath.Join(dbDir, "issues.jsonl")
+	}
+
 	// Look for existing .jsonl files in the .beads directory
 	pattern := filepath.Join(dbDir, "*.jsonl")
 	matches, err := filepath.Glob(pattern)