fix: prevent agents from duplicating delegated subagent work

Addresses user reports where Sisyphus/Hephaestus would delegate tasks
to explore/librarian subagents but then immediately perform the same
search/work themselves, wasting context and defeating the purpose of
delegation.

Changes:
- Add Anti-Duplication section to dynamic-agent-prompt-builder with
  clear rules: once you delegate, do NOT manually re-do the same search
- Update all agent prompts (sisyphus, hephaestus, sis-junior gemini/gpt)
  to use 'non-overlapping work' instead of 'keep working' after delegation
- Add buildAntiDuplicationSection() with explicit examples of forbidden
  vs allowed behavior after delegation
- Add 'Delegation Trust Rule' to explore section
- Add 'Delegation Duplication' to anti-patterns list

Atlas fixes:
- Add AUTO-CONTINUE POLICY to all Atlas variants (default, gemini, gpt)
  preventing the 'should I continue?' confirmation loop between plan steps
- Fix plan file path in default atlas (.sisyphus/tasks/ -> .sisyphus/plans/)
- Update GPT atlas uncertainty section to only ask questions during initial
  plan analysis, not during execution

Fixes: subagent delegation duplication, Atlas continuation prompting

src/agents/atlas/gpt.ts

@@ -48,9 +48,10 @@ Complete ALL tasks in a work plan via \`task()\` until fully done.
 </scope_and_design_constraints>
 
 <uncertainty_and_ambiguity>
-- If a task is ambiguous or underspecified:
+- During initial plan analysis, if a task is ambiguous or underspecified:
   - Ask 1-3 precise clarifying questions, OR
   - State your interpretation explicitly and proceed with the simplest approach.
+- Once execution has started, do NOT stop to ask for continuation or approval between steps.
 - Never fabricate task details, file paths, or requirements.
 - Prefer language like "Based on the plan..." instead of absolute claims.
 - When unsure about parallelization, default to sequential execution.
@@ -134,6 +135,29 @@ Every \`task()\` prompt MUST include ALL 6 sections:
 **Minimum 30 lines per delegation prompt.**
 </delegation_system>
 
+<auto_continue>
+## AUTO-CONTINUE POLICY (STRICT)
+
+**CRITICAL: NEVER ask the user "should I continue", "proceed to next task", or any approval-style questions between plan steps.**
+
+**You MUST auto-continue immediately after verification passes:**
+- After any delegation completes and passes verification → Immediately delegate next task
+- Do NOT wait for user input, do NOT ask "should I continue"
+- Only pause or ask if you are truly blocked by missing information, an external dependency, or a critical failure
+
+**The only time you ask the user:**
+- Plan needs clarification or modification before execution
+- Blocked by an external dependency beyond your control
+- Critical failure prevents any further progress
+
+**Auto-continue examples:**
+- Task A done → Verify → Pass → Immediately start Task B
+- Task fails → Retry 3x → Still fails → Document → Move to next independent task
+- NEVER: "Should I continue to the next task?"
+
+**This is NOT optional. This is core to your role as orchestrator.**
+</auto_continue>
+
 <workflow>
 ## Step 0: Register Tracking