feat(sisyphus_task): enhance error messages with detailed context

Add formatDetailedError helper that includes:
- Full args dump (description, category, agent, skills)
- Session ID and agent info
- Stack trace (first 10 lines)

Applied to all catch blocks for better debugging.

src/tools/sisyphus-task/tools.test.ts

@@ -541,10 +541,12 @@ describe("sisyphus-task", () => {
         toolContext
       )
       
-      // #then - should return error message with the prompt error
+      // #then - should return detailed error message with args and stack trace
       expect(result).toContain("❌")
-      expect(result).toContain("Failed to send prompt")
+      expect(result).toContain("Send prompt failed")
       expect(result).toContain("JSON Parse error")
+      expect(result).toContain("**Arguments**:")
+      expect(result).toContain("**Stack Trace**:")
     })
 
     test("sync mode success returns task result with content", async () => {