Phase C: Automated TLS cert provisioning for L7 routes

Add CertProvisioner that requests TLS certificates from Metacrypt's CA
API during deploy. When a service has L7 routes, the agent checks for
an existing cert, re-issues if missing or within 30 days of expiry,
and writes chain+key to mc-proxy's cert directory before registering
routes.

- Add MetacryptConfig to agent config (server_url, ca_cert, mount,
  issuer, token_path) with defaults and env overrides
- Add CertProvisioner (internal/agent/certs.go): REST client for
  Metacrypt IssueCert, atomic file writes, cert expiry checking
- Wire into Agent struct and deploy flow (before route registration)
- Add hasL7Routes/l7Hostnames helpers in deploy.go
- Fix pre-existing lint issues: unreachable code in portalloc.go,
  gofmt in servicedef.go, gosec suppressions, golangci v2 config
- Update vendored mc-proxy to fix protobuf init panic
- 10 new tests, make all passes with 0 issues

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/config/config_test.go

@@ -163,6 +163,14 @@ func TestLoadAgentConfig(t *testing.T) {
 	if cfg.Log.Level != "debug" {
 		t.Fatalf("log.level: got %q", cfg.Log.Level)
 	}
+
+	// Metacrypt defaults when section is omitted.
+	if cfg.Metacrypt.Mount != "pki" {
+		t.Fatalf("metacrypt.mount default: got %q, want pki", cfg.Metacrypt.Mount)
+	}
+	if cfg.Metacrypt.Issuer != "infra" {
+		t.Fatalf("metacrypt.issuer default: got %q, want infra", cfg.Metacrypt.Issuer)
+	}
 }
 
 func TestCLIConfigValidation(t *testing.T) {
@@ -439,6 +447,80 @@ level = "info"
 	})
 }
 
+func TestAgentConfigMetacrypt(t *testing.T) {
+	cfgStr := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+[metacrypt]
+server_url = "https://metacrypt.metacircular.net:8443"
+ca_cert    = "/etc/mcp/metacircular-ca.pem"
+mount      = "custom-pki"
+issuer     = "custom-issuer"
+token_path = "/srv/mcp/metacrypt-token"
+`
+	path := writeTempConfig(t, cfgStr)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.Metacrypt.ServerURL != "https://metacrypt.metacircular.net:8443" {
+		t.Fatalf("metacrypt.server_url: got %q", cfg.Metacrypt.ServerURL)
+	}
+	if cfg.Metacrypt.CACert != "/etc/mcp/metacircular-ca.pem" {
+		t.Fatalf("metacrypt.ca_cert: got %q", cfg.Metacrypt.CACert)
+	}
+	if cfg.Metacrypt.Mount != "custom-pki" {
+		t.Fatalf("metacrypt.mount: got %q", cfg.Metacrypt.Mount)
+	}
+	if cfg.Metacrypt.Issuer != "custom-issuer" {
+		t.Fatalf("metacrypt.issuer: got %q", cfg.Metacrypt.Issuer)
+	}
+	if cfg.Metacrypt.TokenPath != "/srv/mcp/metacrypt-token" {
+		t.Fatalf("metacrypt.token_path: got %q", cfg.Metacrypt.TokenPath)
+	}
+}
+
+func TestAgentConfigMetacryptEnvOverrides(t *testing.T) {
+	minimal := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+`
+	t.Setenv("MCP_AGENT_METACRYPT_SERVER_URL", "https://override.metacrypt:8443")
+	t.Setenv("MCP_AGENT_METACRYPT_TOKEN_PATH", "/override/token")
+
+	path := writeTempConfig(t, minimal)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.Metacrypt.ServerURL != "https://override.metacrypt:8443" {
+		t.Fatalf("metacrypt.server_url: got %q", cfg.Metacrypt.ServerURL)
+	}
+	if cfg.Metacrypt.TokenPath != "/override/token" {
+		t.Fatalf("metacrypt.token_path: got %q", cfg.Metacrypt.TokenPath)
+	}
+}
+
 func TestDurationParsing(t *testing.T) {
 	tests := []struct {
 		input string