fix(polecat): exclude reserved infrastructure agent names from allocator (#837)

The polecat name allocator was assigning reserved infrastructure agent
names like 'witness' to polecats. Added ReservedInfraAgentNames map
containing witness, mayor, deacon, and refinery. Modified getNames()
to filter these from all themes and custom name lists.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

internal/polecat/namepool_test.go

@@ -462,3 +462,66 @@ func TestThemeForRigDeterministic(t *testing.T) {
 		t.Errorf("theme not deterministic: got %q and %q", theme1, theme2)
 	}
 }
+
+func TestNamePool_ReservedNamesExcluded(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "namepool-test-*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = os.RemoveAll(tmpDir) }()
+
+	// Test all themes to ensure reserved names are excluded
+	for themeName := range BuiltinThemes {
+		pool := NewNamePoolWithConfig(tmpDir, "testrig", themeName, nil, 100)
+
+		// Allocate all available names (up to 100)
+		allocated := make(map[string]bool)
+		for i := 0; i < 100; i++ {
+			name, err := pool.Allocate()
+			if err != nil {
+				t.Fatalf("Allocate error: %v", err)
+			}
+			allocated[name] = true
+		}
+
+		// Verify no reserved names were allocated
+		for reserved := range ReservedInfraAgentNames {
+			if allocated[reserved] {
+				t.Errorf("theme %q allocated reserved name %q", themeName, reserved)
+			}
+		}
+
+		pool.Reset()
+	}
+}
+
+func TestNamePool_ReservedNamesInCustomNames(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "namepool-test-*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = os.RemoveAll(tmpDir) }()
+
+	// Custom names that include reserved names should have them filtered out
+	custom := []string{"alpha", "witness", "beta", "mayor", "gamma"}
+	pool := NewNamePoolWithConfig(tmpDir, "testrig", "", custom, 10)
+
+	// Allocate all names
+	allocated := make(map[string]bool)
+	for i := 0; i < 5; i++ {
+		name, _ := pool.Allocate()
+		allocated[name] = true
+	}
+
+	// Should only get alpha, beta, gamma (3 non-reserved names)
+	// Then overflow names for the remaining allocations
+	if allocated["witness"] {
+		t.Error("allocated reserved name 'witness' from custom names")
+	}
+	if allocated["mayor"] {
+		t.Error("allocated reserved name 'mayor' from custom names")
+	}
+	if !allocated["alpha"] || !allocated["beta"] || !allocated["gamma"] {
+		t.Errorf("expected alpha, beta, gamma to be allocated, got %v", allocated)
+	}
+}