feat: add template system for role contexts and messages

Implements gt-u1j.20: Prompt templates using go:embed.

- Add internal/templates package with embedded .md.tmpl files
- Role templates: mayor, witness, refinery, polecat, crew
- Message templates: spawn, nudge, escalation, handoff
- Update gt prime to use templates with fallback to hardcoded output
- Add crew role detection for <rig>/crew/<name>/ paths
- Include Gas Town architecture overview in all role contexts

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

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

internal/templates/templates_test.go

@@ -0,0 +1,155 @@
+package templates
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	if tmpl == nil {
+		t.Fatal("New() returned nil")
+	}
+}
+
+func TestRenderRole_Mayor(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	data := RoleData{
+		Role:     "mayor",
+		TownRoot: "/test/town",
+		WorkDir:  "/test/town",
+	}
+
+	output, err := tmpl.RenderRole("mayor", data)
+	if err != nil {
+		t.Fatalf("RenderRole() error = %v", err)
+	}
+
+	// Check for key content
+	if !strings.Contains(output, "Mayor Context") {
+		t.Error("output missing 'Mayor Context'")
+	}
+	if !strings.Contains(output, "/test/town") {
+		t.Error("output missing town root")
+	}
+	if !strings.Contains(output, "global coordinator") {
+		t.Error("output missing role description")
+	}
+}
+
+func TestRenderRole_Polecat(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	data := RoleData{
+		Role:     "polecat",
+		RigName:  "myrig",
+		TownRoot: "/test/town",
+		WorkDir:  "/test/town/myrig/polecats/TestCat",
+		Polecat:  "TestCat",
+	}
+
+	output, err := tmpl.RenderRole("polecat", data)
+	if err != nil {
+		t.Fatalf("RenderRole() error = %v", err)
+	}
+
+	// Check for key content
+	if !strings.Contains(output, "Polecat Context") {
+		t.Error("output missing 'Polecat Context'")
+	}
+	if !strings.Contains(output, "TestCat") {
+		t.Error("output missing polecat name")
+	}
+	if !strings.Contains(output, "myrig") {
+		t.Error("output missing rig name")
+	}
+}
+
+func TestRenderMessage_Spawn(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	data := SpawnData{
+		Issue:       "gt-123",
+		Title:       "Test Issue",
+		Priority:    1,
+		Description: "Test description",
+		Branch:      "feature/test",
+		RigName:     "myrig",
+		Polecat:     "TestCat",
+	}
+
+	output, err := tmpl.RenderMessage("spawn", data)
+	if err != nil {
+		t.Fatalf("RenderMessage() error = %v", err)
+	}
+
+	// Check for key content
+	if !strings.Contains(output, "gt-123") {
+		t.Error("output missing issue ID")
+	}
+	if !strings.Contains(output, "Test Issue") {
+		t.Error("output missing issue title")
+	}
+}
+
+func TestRenderMessage_Nudge(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	data := NudgeData{
+		Polecat:    "TestCat",
+		Reason:     "No progress for 30 minutes",
+		NudgeCount: 2,
+		MaxNudges:  3,
+		Issue:      "gt-123",
+		Status:     "in_progress",
+	}
+
+	output, err := tmpl.RenderMessage("nudge", data)
+	if err != nil {
+		t.Fatalf("RenderMessage() error = %v", err)
+	}
+
+	// Check for key content
+	if !strings.Contains(output, "TestCat") {
+		t.Error("output missing polecat name")
+	}
+	if !strings.Contains(output, "2/3") {
+		t.Error("output missing nudge count")
+	}
+}
+
+func TestRoleNames(t *testing.T) {
+	tmpl, err := New()
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	names := tmpl.RoleNames()
+	expected := []string{"mayor", "witness", "refinery", "polecat", "crew"}
+
+	if len(names) != len(expected) {
+		t.Errorf("RoleNames() = %v, want %v", names, expected)
+	}
+
+	for i, name := range names {
+		if name != expected[i] {
+			t.Errorf("RoleNames()[%d] = %q, want %q", i, name, expected[i])
+		}
+	}
+}