update: Hephaestus completion guarantee, Sisyphus-Junior Hephaestus-style rewrite, snake_case tools

Hephaestus:
- Add Completion Guarantee section with Codex-style persistence framing
- Add explicit explore/librarian call syntax examples (subagent_type, not category)
- Use positive 'keep going until resolved' over negative 'NEVER stop'
- Fix tool names: TaskCreate/TaskUpdate → task_create/task_update

Sisyphus-Junior GPT:
- Full Hephaestus-style rewrite: autonomy, reporting, parallelism, tool usage
- Remove Blocked & Allowed Tools section and 'You work ALONE' messaging
- Add Progress Updates, Ambiguity Protocol, Code Quality sections
- Fix tool names: TaskCreate/TaskUpdate → task_create/task_update

Sisyphus-Junior Default:
- Remove buildConstraintsSection and blocked actions messaging
- Fix tool names: TaskCreate/TaskUpdate → task_create/task_update

Tests: update all assertions for new prompt structure (31/31 pass)

src/agents/sisyphus-junior/default.ts

@@ -14,18 +14,15 @@ export function buildDefaultSisyphusJuniorPrompt(
   promptAppend?: string
 ): string {
   const todoDiscipline = buildTodoDisciplineSection(useTaskSystem)
-  const constraintsSection = buildConstraintsSection(useTaskSystem)
   const verificationText = useTaskSystem
     ? "All tasks marked completed"
     : "All todos marked completed"
 
   const prompt = `<Role>
 Sisyphus-Junior - Focused executor from OhMyOpenCode.
-Execute tasks directly. NEVER delegate or spawn other agents.
+Execute tasks directly.
 </Role>
 
-${constraintsSection}
-
 ${todoDiscipline}
 
 <Verification>
@@ -45,36 +42,13 @@ Task NOT complete without:
   return prompt + "\n\n" + resolvePromptAppend(promptAppend)
 }
 
-function buildConstraintsSection(useTaskSystem: boolean): string {
-  if (useTaskSystem) {
-    return `<Critical_Constraints>
-BLOCKED ACTIONS (will fail if attempted):
-- task (agent delegation tool): BLOCKED — you cannot delegate work to other agents
-
-ALLOWED tools:
-- call_omo_agent: You CAN spawn explore/librarian agents for research
-- task_create, task_update, task_list, task_get: ALLOWED — use these for tracking your work
-
-You work ALONE for implementation. No delegation of implementation tasks.
-</Critical_Constraints>`
-  }
-
-  return `<Critical_Constraints>
-BLOCKED ACTIONS (will fail if attempted):
-- task (agent delegation tool): BLOCKED — you cannot delegate work to other agents
-
-ALLOWED: call_omo_agent - You CAN spawn explore/librarian agents for research.
-You work ALONE for implementation. No delegation of implementation tasks.
-</Critical_Constraints>`
-}
-
 function buildTodoDisciplineSection(useTaskSystem: boolean): string {
   if (useTaskSystem) {
     return `<Task_Discipline>
 TASK OBSESSION (NON-NEGOTIABLE):
-- 2+ steps → TaskCreate FIRST, atomic breakdown
-- TaskUpdate(status="in_progress") before starting (ONE at a time)
-- TaskUpdate(status="completed") IMMEDIATELY after each step
+- 2+ steps → task_create FIRST, atomic breakdown
+- task_update(status="in_progress") before starting (ONE at a time)
+- task_update(status="completed") IMMEDIATELY after each step
 - NEVER batch completions
 
 No tasks on multi-step work = INCOMPLETE WORK.