feat(deep): upgrade default model from gpt-5.3-codex to gpt-5.4

Deep category now uses gpt-5.4 as its default model across all providers
(openai, github-copilot, venice, opencode), matching Hephaestus's GPT 5.4
upgrade. The requiresModel constraint is removed since gpt-5.4 is widely
available. Adds openai/gpt-5.3-codex -> openai/gpt-5.4 config migration
for existing user configs. Deep category prompt optimized for GPT 5.4's
stronger native capabilities (leaner, less verbose).

assets/oh-my-opencode.schema.json

@@ -57,7 +57,8 @@
           "cancel-ralph",
           "refactor",
           "start-work",
-          "stop-continuation"
+          "stop-continuation",
+          "remove-ai-slops"
         ]
       }
     },