fix: load types.custom from config.yaml during init auto-import (GH#1225) (#1226)

During bd init, auto-import fails with "invalid issue type" errors even
when types.custom is defined in config.yaml. This happens because custom
types are read from the database, but the database is being created
during init and doesn't have the config set yet.

Changes:
- Add GetCustomTypesFromYAML() to internal/config/config.go to read
  types.custom from config.yaml via viper
- Modify GetCustomTypes() in sqlite/config.go to fallback to config.yaml
  when the database doesn't have types.custom configured
- Add tests for GetCustomTypesFromYAML()

This allows fresh clones with custom types defined in config.yaml (e.g.,
Gas Town types like molecule, gate, convoy, agent, event) to successfully
auto-import their JSONL during bd init.

Fixes GH#1225

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

internal/config/config_test.go

@@ -1442,3 +1442,104 @@ func TestGetSovereigntyInvalid(t *testing.T) {
 		t.Errorf("GetSovereignty() with invalid tier = %q, want %q (fallback)", got, SovereigntyT1)
 	}
 }
+
+func TestGetCustomTypesFromYAML(t *testing.T) {
+	// Isolate from environment variables
+	restore := envSnapshot(t)
+	defer restore()
+
+	// Create a temporary directory with a .beads/config.yaml
+	tmpDir := t.TempDir()
+	beadsDir := filepath.Join(tmpDir, ".beads")
+	if err := os.MkdirAll(beadsDir, 0755); err != nil {
+		t.Fatalf("failed to create .beads directory: %v", err)
+	}
+
+	// Write a config file with types.custom set
+	configContent := `
+types:
+  custom: "molecule,gate,convoy,agent,event"
+`
+	configPath := filepath.Join(beadsDir, "config.yaml")
+	if err := os.WriteFile(configPath, []byte(configContent), 0644); err != nil {
+		t.Fatalf("failed to write config file: %v", err)
+	}
+
+	// Change to tmp directory so config is found
+	t.Chdir(tmpDir)
+
+	// Reset and initialize viper
+	ResetForTesting()
+	if err := Initialize(); err != nil {
+		t.Fatalf("Initialize() returned error: %v", err)
+	}
+
+	// Test GetCustomTypesFromYAML returns the expected types
+	got := GetCustomTypesFromYAML()
+	if got == nil {
+		t.Fatal("GetCustomTypesFromYAML() returned nil, want custom types")
+	}
+
+	expected := []string{"molecule", "gate", "convoy", "agent", "event"}
+	if len(got) != len(expected) {
+		t.Errorf("GetCustomTypesFromYAML() returned %d types, want %d", len(got), len(expected))
+	}
+
+	for i, typ := range expected {
+		if i >= len(got) || got[i] != typ {
+			t.Errorf("GetCustomTypesFromYAML()[%d] = %q, want %q", i, got[i], typ)
+		}
+	}
+}
+
+func TestGetCustomTypesFromYAML_NotSet(t *testing.T) {
+	// Isolate from environment variables
+	restore := envSnapshot(t)
+	defer restore()
+
+	// Create a temporary directory with a .beads/config.yaml WITHOUT types.custom
+	tmpDir := t.TempDir()
+	beadsDir := filepath.Join(tmpDir, ".beads")
+	if err := os.MkdirAll(beadsDir, 0755); err != nil {
+		t.Fatalf("failed to create .beads directory: %v", err)
+	}
+
+	// Write a config file without types.custom
+	configContent := `
+issue-prefix: "test"
+`
+	configPath := filepath.Join(beadsDir, "config.yaml")
+	if err := os.WriteFile(configPath, []byte(configContent), 0644); err != nil {
+		t.Fatalf("failed to write config file: %v", err)
+	}
+
+	// Change to tmp directory
+	t.Chdir(tmpDir)
+
+	// Reset and initialize viper
+	ResetForTesting()
+	if err := Initialize(); err != nil {
+		t.Fatalf("Initialize() returned error: %v", err)
+	}
+
+	// Test GetCustomTypesFromYAML returns nil when not set
+	got := GetCustomTypesFromYAML()
+	if got != nil {
+		t.Errorf("GetCustomTypesFromYAML() = %v, want nil when types.custom not set", got)
+	}
+}
+
+func TestGetCustomTypesFromYAML_NilViper(t *testing.T) {
+	// Save the current viper instance
+	savedV := v
+
+	// Set viper to nil to test nil-safety
+	v = nil
+	defer func() { v = savedV }()
+
+	// Should return nil without panicking
+	got := GetCustomTypesFromYAML()
+	if got != nil {
+		t.Errorf("GetCustomTypesFromYAML() with nil viper = %v, want nil", got)
+	}
+}