feat: add Phase F.2 - The Biographer (memory agent)

Add The Biographer household member for user memory management:

Memory Service (direct access layer):
- src/core/memory_service.py for fast, LLM-free lookups
- Profile, preference, and fact management
- Session context with Redis caching
- Steward integration via prefetch_context()

The Biographer Agent:
- src/agents/biographer/ package with PydanticAI agent
- Discreet chronicler personality for privacy
- Tools: recall_semantic, list_memories, store_insight,
  update_profile, update_preference, forget_memory
- Registered with Household Registry on startup

Steward Integration:
- Memory context pre-fetch during analysis
- Profile/preferences included in Butler note
- Keyword-based context determination

Also includes:
- delegate_to_biographer() wrapper
- 34 new tests (capability + memory service)
- Version bump to 1.2.0

Documentation cleanup:
- Removed obsolete PHASE2_COMPLETE.md, PHASE2_PLAN.md
- Removed docs/library-desk-requirements.md
- Moved ORCHESTRATION_SCENARIOS.md to project root

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/core/startup.py

@@ -5,6 +5,7 @@ Handles initialization of household registry and other startup tasks.
 This module should be called during application startup to register
 all household members.
 """
+from src.agents.biographer import register_biographer
 from src.agents.librarian import register_librarian
 from src.agents.tatlock_core import TATLOCK_CORE_CAPABILITY, tatlock_core_tools
 from src.core.household_registry import get_household_registry
@@ -23,6 +24,7 @@ def register_household_members():
     Currently registers:
     - tatlock_core: Butler's core tools (calculator, datetime, web search)
     - librarian: Research and knowledge management (Phase 3)
+    - biographer: User memory and context management (Phase F)
     """
     registry = get_household_registry()
 
@@ -52,6 +54,16 @@ def register_household_members():
             error=str(e),
         )
 
+    # Register The Biographer (Phase F)
+    try:
+        register_biographer()
+    except Exception as e:
+        # Don't fail startup if Biographer registration fails
+        logger.warning(
+            "biographer_registration_failed",
+            error=str(e),
+        )
+
     logger.info(
         "household_registration_complete",
         total_members=len(registry),