feat: Implement ai_blueprint.md Steps 1 & 2 — bible-tracking merge and character voice profiles

Step 1 (Bible-Tracking Merge):
- Added merge_tracking_to_bible() to story/bible_tracker.py — merges character
  tracking state and lore back into bible dict after each chapter, making
  blueprint_initial.json the single persistent source of truth.
- Integrated in cli/engine.py after each chapter's update_tracking + update_lore_index
  calls so the persisted bible is always up-to-date.

Step 2 (Character-Specific Voice Profiles):
- story/writer.py: write_chapter now checks bp['characters'] for a voice_profile on
  the POV character before falling back to the prebuilt_persona cache.
- story/style_persona.py: refine_persona() accepts pov_character=None; when a POV
  character with a voice_profile is supplied it refines that profile's bio instead of
  the global author_details bio.
- cli/engine.py: refine_persona call now passes ch.get('pov_character') so per-chapter
  persona refinement targets the correct voice.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

story/style_persona.py

@@ -184,11 +184,42 @@ def validate_persona(bp, persona_details, folder):
         return True, 7
 
 
-def refine_persona(bp, text, folder):
+def refine_persona(bp, text, folder, pov_character=None):
     utils.log("SYSTEM", "Refining Author Persona based on recent chapters...")
     ad = bp.get('book_metadata', {}).get('author_details', {})
-    current_bio = ad.get('bio', 'Standard style.')
 
+    # If a POV character is given and has a voice_profile, refine that instead
+    if pov_character:
+        for char in bp.get('characters', []):
+            if char.get('name') == pov_character and char.get('voice_profile'):
+                vp = char['voice_profile']
+                current_bio = vp.get('bio', 'Standard style.')
+                prompt = f"""
+    ROLE: Literary Stylist
+    TASK: Refine a POV character's voice profile based on the text sample.
+
+    INPUT_DATA:
+    - TEXT_SAMPLE: {text[:3000]}
+    - CHARACTER: {pov_character}
+    - CURRENT_VOICE_BIO: {current_bio}
+
+    GOAL: Ensure future chapters for this POV character sound exactly like the sample. Highlight quirks, patterns, vocabulary specific to this character's perspective.
+
+    OUTPUT_FORMAT (JSON): {{ "bio": "Updated voice bio..." }}
+    """
+                try:
+                    response = ai_models.model_logic.generate_content(prompt)
+                    utils.log_usage(folder, ai_models.model_logic.name, response.usage_metadata)
+                    new_bio = json.loads(utils.clean_json(response.text)).get('bio')
+                    if new_bio:
+                        char['voice_profile']['bio'] = new_bio
+                        utils.log("SYSTEM", f"  -> Voice profile bio updated for '{pov_character}'.")
+                except Exception as e:
+                    utils.log("SYSTEM", f"  -> Voice profile refinement failed for '{pov_character}': {e}")
+                return ad  # Return author_details unchanged
+
+    # Default: refine the main author persona bio
+    current_bio = ad.get('bio', 'Standard style.')
     prompt = f"""
     ROLE: Literary Stylist
     TASK: Refine Author Bio based on text sample.