refactor(beads,mail): split large files into focused modules

Break down monolithic beads.go and mail.go into smaller, single-purpose files:

beads package:
- beads_agent.go: Agent-related bead operations
- beads_delegation.go: Delegation bead handling
- beads_dog.go: Dog pool operations
- beads_merge_slot.go: Merge slot management
- beads_mr.go: Merge request operations
- beads_redirect.go: Redirect bead handling
- beads_rig.go: Rig bead operations
- beads_role.go: Role bead management

cmd package:
- mail_announce.go: Announcement subcommand
- mail_check.go: Mail check subcommand
- mail_identity.go: Identity management
- mail_inbox.go: Inbox operations
- mail_queue.go: Queue subcommand
- mail_search.go: Search functionality
- mail_send.go: Send subcommand
- mail_thread.go: Thread operations

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

internal/beads/beads_role.go

@@ -0,0 +1,94 @@
+// Package beads provides role bead management.
+package beads
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Role bead ID naming convention:
+// Role beads are stored in town beads (~/.beads/) with hq- prefix.
+//
+// Canonical format: hq-<role>-role
+//
+// Examples:
+//   - hq-mayor-role
+//   - hq-deacon-role
+//   - hq-witness-role
+//   - hq-refinery-role
+//   - hq-crew-role
+//   - hq-polecat-role
+//
+// Use RoleBeadIDTown() to get canonical role bead IDs.
+// The legacy RoleBeadID() function returns gt-<role>-role for backward compatibility.
+
+// RoleBeadID returns the role bead ID for a given role type.
+// Role beads define lifecycle configuration for each agent type.
+// Deprecated: Use RoleBeadIDTown() for town-level beads with hq- prefix.
+// Role beads are global templates and should use hq-<role>-role, not gt-<role>-role.
+func RoleBeadID(roleType string) string {
+	return "gt-" + roleType + "-role"
+}
+
+// DogRoleBeadID returns the Dog role bead ID.
+func DogRoleBeadID() string {
+	return RoleBeadID("dog")
+}
+
+// MayorRoleBeadID returns the Mayor role bead ID.
+func MayorRoleBeadID() string {
+	return RoleBeadID("mayor")
+}
+
+// DeaconRoleBeadID returns the Deacon role bead ID.
+func DeaconRoleBeadID() string {
+	return RoleBeadID("deacon")
+}
+
+// WitnessRoleBeadID returns the Witness role bead ID.
+func WitnessRoleBeadID() string {
+	return RoleBeadID("witness")
+}
+
+// RefineryRoleBeadID returns the Refinery role bead ID.
+func RefineryRoleBeadID() string {
+	return RoleBeadID("refinery")
+}
+
+// CrewRoleBeadID returns the Crew role bead ID.
+func CrewRoleBeadID() string {
+	return RoleBeadID("crew")
+}
+
+// PolecatRoleBeadID returns the Polecat role bead ID.
+func PolecatRoleBeadID() string {
+	return RoleBeadID("polecat")
+}
+
+// GetRoleConfig looks up a role bead and returns its parsed RoleConfig.
+// Returns nil, nil if the role bead doesn't exist or has no config.
+func (b *Beads) GetRoleConfig(roleBeadID string) (*RoleConfig, error) {
+	issue, err := b.Show(roleBeadID)
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	if !HasLabel(issue, "gt:role") {
+		return nil, fmt.Errorf("bead %s is not a role bead (missing gt:role label)", roleBeadID)
+	}
+
+	return ParseRoleConfig(issue.Description), nil
+}
+
+// HasLabel checks if an issue has a specific label.
+func HasLabel(issue *Issue, label string) bool {
+	for _, l := range issue.Labels {
+		if l == label {
+			return true
+		}
+	}
+	return false
+}