fix(keyword-detector): skip keyword detection for background task sessions

Skip all keyword detection for background task sessions to prevent mode
injection (e.g., [analyze-mode], [search-mode]) which incorrectly triggers
Prometheus planner restrictions on Sisyphus sessions.

This aligns with the existing pattern used in:
- sisyphus-orchestrator (line 504)
- todo-continuation-enforcer (line 303)
- session-notification (line 278)

Closes #713

assets/oh-my-opencode.schema.json

@@ -72,12 +72,11 @@
           "empty-message-sanitizer",
           "thinking-block-validator",
           "ralph-loop",
-          "preemptive-compaction",
           "compaction-context-injector",
           "claude-code-hooks",
           "auto-slash-command",
           "edit-error-recovery",
-          "sisyphus-task-retry",
+          "delegate-task-retry",
           "prometheus-md-only",
           "start-work",
           "sisyphus-orchestrator"
@@ -2134,14 +2133,6 @@
         "auto_resume": {
           "type": "boolean"
         },
-        "preemptive_compaction": {
-          "type": "boolean"
-        },
-        "preemptive_compaction_threshold": {
-          "type": "number",
-          "minimum": 0.5,
-          "maximum": 0.95
-        },
         "truncate_all_tool_outputs": {
           "type": "boolean"
         },
@@ -2234,9 +2225,6 @@
               }
             }
           }
-        },
-        "dcp_for_compaction": {
-          "type": "boolean"
         }
       }
     },