feat(tools): support toggling send_file tool via config

Add SendFileConfig with Enabled field to ToolsConfig, defaulting to
true. Wrap send_file tool registration in loop.go with the config
check, consistent with the pattern used by other tools.

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

pkg/agent/loop.go

@@ -171,13 +171,15 @@ func registerSharedTools(
 		}
 
 		// Send file tool (outbound media via MediaStore — store injected later by SetMediaStore)
-		sendFileTool := tools.NewSendFileTool(
-			agent.Workspace,
-			cfg.Agents.Defaults.RestrictToWorkspace,
-			cfg.Agents.Defaults.GetMaxMediaSize(),
-			nil,
-		)
-		agent.Tools.Register(sendFileTool)
+		if cfg.Tools.IsToolEnabled("send_file") {
+			sendFileTool := tools.NewSendFileTool(
+				agent.Workspace,
+				cfg.Agents.Defaults.RestrictToWorkspace,
+				cfg.Agents.Defaults.GetMaxMediaSize(),
+				nil,
+			)
+			agent.Tools.Register(sendFileTool)
+		}
 
 		// Skill discovery and installation tools
 		skills_enabled := cfg.Tools.IsToolEnabled("skills")

pkg/config/config.go

@@ -626,6 +626,7 @@ type ToolsConfig struct {
 	ListDir         ToolConfig         `json:"list_dir"                                                 envPrefix:"PICOCLAW_TOOLS_LIST_DIR_"`
 	Message         ToolConfig         `json:"message"                                                  envPrefix:"PICOCLAW_TOOLS_MESSAGE_"`
 	ReadFile        ToolConfig         `json:"read_file"                                                envPrefix:"PICOCLAW_TOOLS_READ_FILE_"`
+	SendFile        ToolConfig         `json:"send_file"                                                envPrefix:"PICOCLAW_TOOLS_SEND_FILE_"`
 	Spawn           ToolConfig         `json:"spawn"                                                    envPrefix:"PICOCLAW_TOOLS_SPAWN_"`
 	SPI             ToolConfig         `json:"spi"                                                      envPrefix:"PICOCLAW_TOOLS_SPI_"`
 	Subagent        ToolConfig         `json:"subagent"                                                 envPrefix:"PICOCLAW_TOOLS_SUBAGENT_"`
@@ -899,6 +900,8 @@ func (t *ToolsConfig) IsToolEnabled(name string) bool {
 		return t.Subagent.Enabled
 	case "web_fetch":
 		return t.WebFetch.Enabled
+	case "send_file":
+		return t.SendFile.Enabled
 	case "write_file":
 		return t.WriteFile.Enabled
 	case "mcp":

pkg/config/defaults.go

@@ -403,6 +403,9 @@ func DefaultConfig() *Config {
 					TTLSeconds: 300,
 				},
 			},
+			SendFile: ToolConfig{
+				Enabled: true,
+			},
 			MCP: MCPConfig{
 				ToolConfig: ToolConfig{
 					Enabled: false,