feat(keyword-detector): add per-keyword disable config

Adds keyword_detector.disabled_keywords config so users can opt out of
specific keyword detectors individually without disabling the entire
keyword-detector hook. Allowed values: 'ultrawork', 'search', 'analyze',
'team'. Default empty/missing -> all four detectors active (no behavior
change for existing configs).

Motivation: an audit revealed search and analyze patterns trigger on
~30-60% of normal conversational user messages (e.g. 'how to', 'why is',
'show me', '왜', '어떻게'). The disable list is the immediate kill switch
while the patterns themselves are tightened in a separate PR.

Schema follows the existing per-feature config block convention shared
by team_mode, ralph_loop, runtime_fallback, and comment_checker. The
KeywordType enum (z.enum) lives next to the config schema and is
re-imported by the detector to keep the union type in lockstep with the
schema.

Threading:
  pluginConfig.keyword_detector
    -> create-transform-hooks.ts (factory wiring)
    -> createKeywordDetectorHook(config)
    -> detectKeywordsWithType(text, agent, model, disabledKeywords)
    -> Set-based filter at the source-of-truth detector

Adds 8 regression tests covering per-keyword disable, multi-keyword
disable, partial disable (one keyword off, another still firing),
ultrawork toast suppression, undefined config, and empty array.

src/hooks/keyword-detector/AGENTS.md

@@ -47,11 +47,24 @@ chat.message (user input)
   → extractPromptText(parts)
   → isSystemDirective? → skip
   → removeSystemReminders(text)  # strip <SYSTEM_REMINDER> blocks
-  → detectKeywordsWithType(cleanText, agentName, modelID)
+  → detectKeywordsWithType(cleanText, agentName, modelID, disabledKeywords)
   → isPlannerAgent(agentName)? → filter out ultrawork
   → for each detected keyword: inject mode message into output
 ```
 
+## CONFIG
+
+```jsonc
+{
+  "keyword_detector": {
+    // Skip injection for any keyword in this list. Allowed: "ultrawork", "search", "analyze", "team".
+    "disabled_keywords": ["search", "analyze"]
+  }
+}
+```
+
+Default: empty/missing → all four detectors active. Schema lives at [src/config/schema/keyword-detector.ts](../../config/schema/keyword-detector.ts).
+
 ## GUARDS
 
 - **System directive skip**: Messages tagged as system directives are not scanned (prevents infinite loops)