feat: add [runners] config section to toggle each runner on/off

Adds RunnersConfig{Claude,Gemini,Local,Container *bool} to Config,
parsed from a [runners] TOML section. Each field uses the *bool pointer
pattern (nil = enabled by default, false = disabled) so existing installs
require no config changes.

serve.go / run.go now gate each runner registration on the corresponding
Enabled() method. The pool's runners map remains the authoritative
routing table — absent entries are already skipped by pickAgent and
fail-fast in getRunner, so no executor changes are needed.

Example:
  [runners]
  gemini = false   # disable cloud gemini runner
  local  = true    # explicit (same as default)

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

1 files changed, 10 insertions, 6 deletions

diff --git a/internal/cli/run.go b/internal/cli/run.go
index 48f34b7..771c7b7 100644
--- a/internal/cli/run.go
+++ b/internal/cli/run.go
@@ -77,8 +77,10 @@ func runTasks(file string, parallel int, dryRun bool) error {
 		apiURL = "http://" + cfg.ServerAddr
 	}
 
-	runners := map[string]executor.Runner{
-		"claude": &executor.ContainerRunner{
+	runners := map[string]executor.Runner{}
+
+	if cfg.Runners.ClaudeEnabled() {
+		runners["claude"] = &executor.ContainerRunner{
 			Image:        cfg.ClaudeImage,
 			Logger:       logger,
 			LogDir:       cfg.LogDir,
@@ -87,8 +89,10 @@ func runTasks(file string, parallel int, dryRun bool) error {
 			SSHAuthSock:  cfg.SSHAuthSock,
 			ClaudeBinary: cfg.ClaudeBinaryPath,
 			GeminiBinary: cfg.GeminiBinaryPath,
-		},
-		"gemini": &executor.ContainerRunner{
+		}
+	}
+	if cfg.Runners.GeminiEnabled() {
+		runners["gemini"] = &executor.ContainerRunner{
 			Image:        cfg.GeminiImage,
 			Logger:       logger,
 			LogDir:       cfg.LogDir,
@@ -97,11 +101,11 @@ func runTasks(file string, parallel int, dryRun bool) error {
 			SSHAuthSock:  cfg.SSHAuthSock,
 			ClaudeBinary: cfg.ClaudeBinaryPath,
 			GeminiBinary: cfg.GeminiBinaryPath,
-		},
+		}
 	}
 
 	localClient := buildLocalLLMClient(cfg.LocalModel, logger)
-	if localClient != nil {
+	if localClient != nil && cfg.Runners.LocalEnabled() {
 		runners["local"] = &executor.LocalRunner{
 			Client:             localClient,
 			Logger:             logger,