feat(agents): add centralized GPT apply_patch permission guard

Extract hardcoded GPT apply_patch permission logic into a reusable module
to ensure consistent behavior across all agents. This prevents GPT models
from using the unreliable apply_patch tool while allowing other models.

- Add gpt-apply-patch-guard.ts with GPT_APPLY_PATCH_GUIDANCE and getGptApplyPatchPermission
- Update Hephaestus agent to use centralized permission logic
- Update Sisyphus-Junior agent to use centralized permission logic
- Update all GPT prompt builders to reference shared guidance constant

🤖 Generated with assistance of OhMyOpenCode

src/agents/sisyphus/gpt-5-4.ts

@@ -21,6 +21,7 @@
  *   8. <style>             - Tone (prose) + output contract + progress updates
  */
 
+import { GPT_APPLY_PATCH_GUIDANCE } from "../gpt-apply-patch-guard";
 import type {
   AvailableAgent,
   AvailableTool,
@@ -310,7 +311,7 @@ Every implementation task follows this cycle. No exceptions.
    Skills: if ANY available skill's domain overlaps with the task, load it NOW via \`skill\` tool and include it in \`load_skills\`. When the connection is even remotely plausible, load the skill - the cost of loading an irrelevant skill is near zero, the cost of missing a relevant one is high.
 
 4. EXECUTE_OR_SUPERVISE -
-   If self: surgical changes, match existing patterns, minimal diff. Never suppress type errors. Never commit unless asked. Bugfix rule: fix minimally, never refactor while fixing. Use the \`edit\` and \`write\` tools for file changes. Do not use \`apply_patch\` on GPT models - it is unreliable here and can hang during verification.
+   If self: surgical changes, match existing patterns, minimal diff. Never suppress type errors. Never commit unless asked. Bugfix rule: fix minimally, never refactor while fixing. ${GPT_APPLY_PATCH_GUIDANCE}
    If delegated: exhaustive 6-section prompt per \`<delegation>\` protocol. Session continuity for follow-ups.
 
 5. VERIFY -