feat: crew attach auto-detection, worktree polecats, beads mail

- gt crew at: auto-detect crew from cwd, run gt prime after launch
- Polecats now use git worktrees from refinery (faster than clones)
- Updated architecture.md for two-tier beads mail model
- Town beads (gm-*) for Mayor mail/coordination
- Rig .beads/ symlinks to refinery/rig/.beads

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

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

internal/config/loader_test.go

@@ -8,7 +8,7 @@ import (
 
 func TestTownConfigRoundTrip(t *testing.T) {
 	dir := t.TempDir()
-	path := filepath.Join(dir, "config", "town.json")
+	path := filepath.Join(dir, "mayor", "town.json")
 
 	original := &TownConfig{
 		Type:      "town",
@@ -36,7 +36,7 @@ func TestTownConfigRoundTrip(t *testing.T) {
 
 func TestRigsConfigRoundTrip(t *testing.T) {
 	dir := t.TempDir()
-	path := filepath.Join(dir, "config", "rigs.json")
+	path := filepath.Join(dir, "mayor", "rigs.json")
 
 	original := &RigsConfig{
 		Version: 1,