feat(keyword-detector): add enabled_expansions config for allowlist control

Add optional enabled_expansions field to keyword_detector config schema.
When set, acts as an allowlist - only those expansion types fire.
Empty array disables all expansions. Absent field keeps all enabled (backward-compatible).
Also supports coexistence with disabled_keywords denylist for fine-grained control.

- src/config/schema/keyword-detector.ts: add enabled_expansions field
- src/hooks/keyword-detector/detector.ts: apply allowlist filter in detectKeywordsWithType
- src/hooks/keyword-detector/hook.ts: pass enabled_expansions from config
- src/hooks/keyword-detector/index.test.ts: add 4 tests for enabled_expansions behavior
- assets/oh-my-opencode.schema.json: regenerate schema

assets/oh-my-opencode.schema.json

@@ -6026,6 +6026,20 @@
     "keyword_detector": {
       "type": "object",
       "properties": {
+        "enabled_expansions": {
+          "type": "array",
+          "items": {
+            "type": "string",
+            "enum": [
+              "ultrawork",
+              "search",
+              "analyze",
+              "team",
+              "hyperplan",
+              "hyperplan-ultrawork"
+            ]
+          }
+        },
         "disabled_keywords": {
           "type": "array",
           "items": {