refactor(prompts): replace markdown tables with bullet lists, harden Oracle protection

Convert all markdown tables in Sisyphus and dynamic-agent-prompt-builder
to plain bullet lists for cleaner prompt rendering.

Add explicit Oracle safeguards:
- Hard Block: background_cancel(all=true) when Oracle running
- Hard Block: delivering final answer before collecting Oracle result
- Anti-Pattern: background_cancel(all=true) and skipping Oracle
- Oracle section: NEVER cancel, collect via background_output first
- Background Result Collection: split cancel/wait into separate steps
  with explicit NEVER use background_cancel(all=true) instruction

src/agents/dynamic-agent-prompt-builder.test.ts

@@ -64,8 +64,8 @@ describe("buildCategorySkillsDelegationGuide", () => {
     const result = buildCategorySkillsDelegationGuide(categories, allSkills)
 
     //#then: should show source for each custom skill
-    expect(result).toContain("| user |")
-    expect(result).toContain("| project |")
+    expect(result).toContain("(user)")
+    expect(result).toContain("(project)")
   })
 
   it("should not show custom skill section when only builtin skills exist", () => {