feat(M34): dynamic issuer configuration with encrypted config storage

Replace static env-var-based issuer wiring with GUI-driven dynamic
configuration stored encrypted in PostgreSQL. Operators can now
configure, test, enable/disable, and manage issuers from the dashboard
without restarting the server.

Key changes:
- AES-256-GCM encryption for sensitive issuer config at rest (PBKDF2
  key derivation with 100k iterations)
- Dynamic IssuerRegistry with sync.RWMutex replacing static map
- Connector factory pattern (issuerfactory.NewFromConfig) replacing
  140 lines of static wiring in main.go
- Migration 000009: encrypted_config, last_tested_at, test_status,
  source columns on issuers table
- Env var seeding on first boot with ON CONFLICT DO NOTHING
- Registry Rebuild() for atomic map swap after CRUD operations
- Issuer type validation against domain constants on Create
- Audit trail for test connection results
- Conditional seeding for step-ca/OpenSSL (only when env vars set)
- GUI: source badge, connection test status on issuer detail page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/connector/issuerfactory/factory.go

@@ -0,0 +1,87 @@
+package issuerfactory
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+
+	"github.com/shankar0123/certctl/internal/connector/issuer"
+	"github.com/shankar0123/certctl/internal/connector/issuer/acme"
+	"github.com/shankar0123/certctl/internal/connector/issuer/digicert"
+	"github.com/shankar0123/certctl/internal/connector/issuer/googlecas"
+	"github.com/shankar0123/certctl/internal/connector/issuer/local"
+	"github.com/shankar0123/certctl/internal/connector/issuer/openssl"
+	"github.com/shankar0123/certctl/internal/connector/issuer/sectigo"
+	"github.com/shankar0123/certctl/internal/connector/issuer/stepca"
+	"github.com/shankar0123/certctl/internal/connector/issuer/vault"
+)
+
+// NewFromConfig instantiates an issuer connector from its type string and config JSON.
+// The config JSON keys use snake_case matching the connector Config struct json tags.
+// This replaces the manual wiring in cmd/server/main.go.
+func NewFromConfig(issuerType string, configJSON json.RawMessage, logger *slog.Logger) (issuer.Connector, error) {
+	if len(configJSON) == 0 {
+		configJSON = []byte("{}")
+	}
+
+	switch issuerType {
+	case "local", "GenericCA":
+		var cfg local.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid Local CA config: %w", err)
+		}
+		return local.New(&cfg, logger), nil
+
+	case "ACME":
+		var cfg acme.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid ACME config: %w", err)
+		}
+		return acme.New(&cfg, logger), nil
+
+	case "StepCA":
+		var cfg stepca.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid step-ca config: %w", err)
+		}
+		return stepca.New(&cfg, logger), nil
+
+	case "OpenSSL":
+		var cfg openssl.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid OpenSSL config: %w", err)
+		}
+		return openssl.New(&cfg, logger), nil
+
+	case "VaultPKI":
+		var cfg vault.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid Vault PKI config: %w", err)
+		}
+		return vault.New(&cfg, logger), nil
+
+	case "DigiCert":
+		var cfg digicert.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid DigiCert config: %w", err)
+		}
+		return digicert.New(&cfg, logger), nil
+
+	case "Sectigo":
+		var cfg sectigo.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid Sectigo config: %w", err)
+		}
+		return sectigo.New(&cfg, logger), nil
+
+	case "GoogleCAS":
+		var cfg googlecas.Config
+		if err := json.Unmarshal(configJSON, &cfg); err != nil {
+			return nil, fmt.Errorf("invalid Google CAS config: %w", err)
+		}
+		return googlecas.New(&cfg, logger), nil
+
+	default:
+		return nil, fmt.Errorf("unknown issuer type: %q", issuerType)
+	}
+}