feat(journal): LLM tools (record_moment, search_journal) + system prompt wiring

- services/tools/journal.py — record_moment + search_journal tool handlers
- services/tools/_registry.py: add `journal` flag on ToolDef + tool() decorator
- get_tools_for_user(user_id, conversation_type='chat'|'journal') —
  exclude journal-only tools from chat sessions; exclude set_rag_scope
  from journal sessions
- services/tools/__init__.py: register the new journal module; drop the
  unused get_briefing_tools export
- services/llm.py build_context: short-circuit for journal conversations,
  using journal_pipeline.build_journal_system_prompt and skipping all
  notes-RAG injection (preserves the journal/notes isolation invariant)
- services/generation_task.py: pass conversation_type into get_tools_for_user

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/fabledassistant/services/tools/__init__.py

@@ -10,6 +10,7 @@ of the app depends on.
 from fabledassistant.services.tools import (  # noqa: F401
     calendar,
     entities,
+    journal,
     notes,
     profile,
     projects,
@@ -22,12 +23,10 @@ from fabledassistant.services.tools import (  # noqa: F401
 )
 from fabledassistant.services.tools._registry import (
     execute_tool,
-    get_briefing_tools,
     get_tools_for_user,
 )
 
 __all__ = [
     "execute_tool",
-    "get_briefing_tools",
     "get_tools_for_user",
 ]