feat: Implement Phase 5 Quest System (100% complete)

Add YAML-driven quest system with context-aware offering:

Core Implementation:
- Quest data models (Quest, QuestObjective, QuestReward, QuestTriggers)
- QuestService for YAML loading and caching
- QuestEligibilityService with level, location, and probability filtering
- LoreService stub (MockLoreService) ready for Phase 6 Weaviate integration

Quest Content:
- 5 example quests across difficulty tiers (2 easy, 2 medium, 1 hard)
- Quest-centric design: quests define their NPC givers
- Location-based probability weights for natural quest offering

AI Integration:
- Quest offering section in npc_dialogue.j2 template
- Response parser extracts [QUEST_OFFER:quest_id] markers
- AI naturally weaves quest offers into NPC conversations

API Endpoints:
- POST /api/v1/quests/accept - Accept quest offer
- POST /api/v1/quests/decline - Decline quest offer
- POST /api/v1/quests/progress - Update objective progress
- POST /api/v1/quests/complete - Complete quest, claim rewards
- POST /api/v1/quests/abandon - Abandon active quest
- GET /api/v1/characters/{id}/quests - List character quests
- GET /api/v1/quests/{quest_id} - Get quest details

Frontend:
- Quest tracker sidebar with HTMX integration
- Quest offer modal for accept/decline flow
- Quest detail modal for viewing progress
- Combat service integration for kill objective tracking

Testing:
- Unit tests for Quest models and serialization
- Integration tests for full quest lifecycle
- Comprehensive test coverage for eligibility service

Documentation:
- Reorganized docs into /docs/phases/ structure
- Added Phase 5-12 planning documents
- Updated ROADMAP.md with new structure

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

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

api/app/ai/narrative_generator.py

@@ -447,7 +447,8 @@ class NarrativeGenerator:
         user_tier: UserTier,
         npc_relationship: str | None = None,
         previous_dialogue: list[dict[str, Any]] | None = None,
-        npc_knowledge: list[str] | None = None
+        npc_knowledge: list[str] | None = None,
+        quest_offering_context: dict[str, Any] | None = None
     ) -> NarrativeResponse:
         """
         Generate NPC dialogue in response to player conversation.
@@ -461,6 +462,7 @@ class NarrativeGenerator:
             npc_relationship: Optional description of relationship with NPC.
             previous_dialogue: Optional list of previous exchanges.
             npc_knowledge: Optional list of things this NPC knows about.
+            quest_offering_context: Optional quest offer context from QuestEligibilityService.
 
         Returns:
             NarrativeResponse with NPC dialogue.
@@ -500,6 +502,7 @@ class NarrativeGenerator:
                 npc_relationship=npc_relationship,
                 previous_dialogue=previous_dialogue or [],
                 npc_knowledge=npc_knowledge or [],
+                quest_offering_context=quest_offering_context,
                 max_tokens=model_config.max_tokens
             )
         except PromptTemplateError as e: