enhance: support client certificates for mutual TLS (#1273)

Add `runner.client_cert_file` and `runner.client_key_file` for Gitea instances that require mutual TLS. The runner presents the certificate on its RPCs, job summary uploads, and the action, reusable workflow and `builtin:checkout` clones from the instance. The files are read on use, so renewed certificates apply without a restart. Job steps do not get them. An incomplete or mismatched pair fails startup.

Clones now decide the token, client certificate and `runner.insecure` with one host check, which also gives reusable workflow clones the TLS settings they lacked. `runner.insecure` still only covers the registered address.

Fixes: https://gitea.com/gitea/runner/issues/321
Co-authored-by: silverwind <[email protected]>
Co-authored-by: silverwind <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1273
Reviewed-by: silverwind <[email protected]>
Co-authored-by: bircni <[email protected]>

internal/app/cmd/daemon.go

@@ -170,7 +170,7 @@ func runDaemon(ctx context.Context, daemArgs *daemonArgs, configFile *string) fu
 
 		cli := client.New(
 			reg.Address,
-			cfg.Runner.Insecure,
+			cfg.Runner.TLSConfig(),
 			reg.UUID,
 			reg.Token,
 			config.RequestTimeout,

internal/app/cmd/register.go

@@ -363,7 +363,7 @@ func doRegister(ctx context.Context, cfg *config.Config, inputs *registerInputs)
 	// initial http client
 	cli := client.New(
 		inputs.InstanceAddr,
-		cfg.Runner.Insecure,
+		cfg.Runner.TLSConfig(),
 		"",
 		"",
 		config.RequestTimeout,