refactor(tools): rename agent parameter to subagent_type in sisyphus_task

- Update parameter name from 'agent' to 'subagent_type' for consistency with call_omo_agent
- Update all references and error messages
- Remove deprecated 'agent' field from SisyphusTaskArgs interface
- Update git-master skill documentation to reflect parameter name change

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/features/builtin-skills/git-master/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: git-master
-description: "Use for: (1) committing changes atomically, (2) rebasing/squashing/cleaning history, (3) finding when/who changed specific code (git blame, bisect, log -S). Triggers: 'commit', 'rebase', 'squash', 'who wrote', 'when was X added', 'find the commit that'."
+description: "MUST USE for ANY git operations. Atomic commits, rebase/squash, history search (blame, bisect, log -S). STRONGLY RECOMMENDED: Use with sisyphus_task(category='quick', skills=['git-master'], ...) to save context. Triggers: 'commit', 'rebase', 'squash', 'who wrote', 'when was X added', 'find the commit that'."
 ---
 
 # Git Master Agent

src/features/builtin-skills/skills.ts

@@ -95,7 +95,7 @@ Interpret creatively and make unexpected choices that feel genuinely designed fo
 const gitMasterSkill: BuiltinSkill = {
   name: "git-master",
   description:
-    "MUST USE for ANY git operations. Atomic commits, rebase/squash, history search (blame, bisect, log -S). STRONGLY RECOMMENDED: use with sisyphus_task(category='quick', skills=['git-master'], ...) to save context. Triggers: 'commit', 'rebase', 'squash', 'who wrote', 'when was X added', 'find the commit that'.",
+    "MUST USE for ANY git operations. Atomic commits, rebase/squash, history search (blame, bisect, log -S). STRONGLY RECOMMENDED: Use with sisyphus_task(category='quick', skills=['git-master'], ...) to save context. Triggers: 'commit', 'rebase', 'squash', 'who wrote', 'when was X added', 'find the commit that'.",
   template: `# Git Master Agent
 
 You are a Git expert combining three specializations:

src/tools/sisyphus-task/tools.ts

@@ -98,8 +98,8 @@ export function createSisyphusTask(options: SisyphusTaskToolOptions): ToolDefini
     args: {
       description: tool.schema.string().describe("Short task description"),
       prompt: tool.schema.string().describe("Full detailed prompt for the agent"),
-      category: tool.schema.string().optional().describe(`Category name (e.g., ${CATEGORY_EXAMPLES}). Mutually exclusive with agent.`),
-      agent: tool.schema.string().optional().describe("Agent name directly (e.g., 'oracle', 'explore'). Mutually exclusive with category."),
+      category: tool.schema.string().optional().describe(`Category name (e.g., ${CATEGORY_EXAMPLES}). Mutually exclusive with subagent_type.`),
+      subagent_type: tool.schema.string().optional().describe("Agent name directly (e.g., 'oracle', 'explore'). Mutually exclusive with category."),
       background: tool.schema.boolean().describe("Run in background. MUST be explicitly set. Use false for task delegation, true only for parallel exploration."),
       resume: tool.schema.string().optional().describe("Session ID to resume - continues previous agent session with full context"),
       skills: tool.schema.array(tool.schema.string()).optional().describe("Array of skill names to prepend to the prompt. Skills will be resolved and their content prepended with a separator."),
@@ -160,12 +160,12 @@ Use \`background_output\` with task_id="${task.id}" to check progress.`
         }
       }
 
-      if (args.category && args.agent) {
-        return `❌ Invalid arguments: Provide EITHER category OR agent, not both.`
+      if (args.category && args.subagent_type) {
+        return `❌ Invalid arguments: Provide EITHER category OR subagent_type, not both.`
       }
 
-      if (!args.category && !args.agent) {
-        return `❌ Invalid arguments: Must provide either category or agent.`
+      if (!args.category && !args.subagent_type) {
+        return `❌ Invalid arguments: Must provide either category or subagent_type.`
       }
 
       let agentToUse: string
@@ -181,7 +181,7 @@ Use \`background_output\` with task_id="${task.id}" to check progress.`
         agentToUse = SISYPHUS_JUNIOR_AGENT
         categoryModel = parseModelString(resolved.config.model)
       } else {
-        agentToUse = args.agent!.trim()
+        agentToUse = args.subagent_type!.trim()
         if (!agentToUse) {
           return `❌ Agent name cannot be empty.`
         }

src/tools/sisyphus-task/types.ts

@@ -2,7 +2,7 @@ export interface SisyphusTaskArgs {
   description: string
   prompt: string
   category?: string
-  agent?: string
+  subagent_type?: string
   background: boolean
   resume?: string
   skills?: string[]