feat: Codex/Responses API compatibility, cache TTL 24h, prompt optimization, n8n test tools, gitignore cleanup

- NEW: store_search_tool.py - query dedicated store table
- NEW: store_search_tool.txt - tool prompt
- UPDATE: brand_knowledge_tool.py - pure semantic search
- UPDATE: product_mapping.py - fuzzy match for typos
- UPDATE: system_prompt.txt - section 5.5.1 canifa_store_search
- UPDATE: get_tools.py + prompt_utils.py - register new tool
- UPDATE: promotion_canifa_tool.py - new salerule table
- All prompts pushed to Langfuse

refactor: improve system prompt - anti-fabrication, body comment ban, price handling, stylist mode, response length limits, Langfuse cache hit trace

- Replace description_text_full with description_text in vector search (reduce token bloat)
- Add description_text to CASE 1 (code search) and CASE 3 (vector search)
- Fix generic word fallback: 'quần bán chạy' now filters correctly
- Derive GENERIC_WORDS from PRODUCT_LINE_MAP (auto-sync)
- Fix duplicate if include_product_ids in conversation_manager.py
- Add product_mapping.py with PRODUCT_LINE_MAP and resolve functions

- Add master_color as explicit SQL FILTER field in SearchItem (was in description)
- Add LIKE filter in _get_metadata_clauses for master_color + product_color_name
- Add MAX_BY(master_color) to final SELECT aggregation
- Fix color fallback in format_product_results (parse from description_text_full)
- Strengthen Rule 3a: specific design/pattern matching (con lợn, Disney, etc.)
- Add thảo mai exception: truthfulness > flattery when no products match
- Update tool prompt examples to use master_color as separate field

fix: accessory filter mapping - use actual DB product_line_vn values for accessories (Khan, Mu, Tat, Tui xach, Chan ca nhan etc.) + remove 8-product truncation limit + add accessory guidance in prompts

fix: disable strict filters (sleeve, style, fitting, neckline, material, season) - only keep name, gender, age, color

feat: optimize filter performance and rename query to description - Pre-compile regex patterns for filter optimization - Rename SearchItem.query to SearchItem.description for semantic search - Add váy đầm, váy bé gái to product_map - Fix price format (remove decimal) - Tune LIMIT values for vector search

Update prompt: Enhance [NEXT] strategy, improve writing style, refine [GOAL] handling, and inject insight into prompt