fix: revert load_skills default and enforce via prompts instead

Revert .default([]) on load_skills schema back to required, restore the runtime error for missing load_skills, and add explicit load_skills=[] to all task() examples in agent prompts that were missing it.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/agents/prometheus/high-accuracy-mode.ts

@@ -17,6 +17,7 @@ export const PROMETHEUS_HIGH_ACCURACY_MODE = `# PHASE 3: PLAN GENERATION
 while (true) {
   const result = task(
     subagent_type="momus",
+    load_skills=[],
     prompt=".sisyphus/plans/{name}.md",
     run_in_background=false
   )