feat: add model selector dropdown to UI

feat: rewrite gap cards with severity support and generic rendering

fix: ask agent confirm now correctly updates plan card fields

fix: address code review issues - notes persistence, XSS, value extraction order

feat: unified confirm/revise auto-fills plan card fields

feat: editable plan card with field edit, ask agent, notes, save & continue

feat: add i18n strings for editable plan card

feat: add CSS for editable plan card controls

fix: include geometry stats in CrewOrchestrator preview to prevent toFixed crash

fix: question cards use batch selection with single Submit button

feat: add frontend question cards with gap card rendering and interaction handlers

fix: path traversal in model endpoints, XSS in plan card, remove dead code

feat: add Chat/Guided tab switcher, wizard, plan card, 3MF downloads, i18n

feat(frontend): add 3D toolpath renderer, view toggle, and G-code download

feat(frontend): add G-code parser with G0/G1/G2/G3 and arc tessellation

feat: add i18n support for English, Traditional Chinese, Vietnamese

feat: add confirm/revise buttons to agent recommendations

feat: add STEP/STL download links to gallery cards, persist models from server

fix: surface CAD execution errors to user instead of silently failing

feat: remove mock/claude backends, default to gemini, add openai toggle

feat: add DesignState memory + localStorage persistence

fix: prevent Gemini from repeating responses

feat: add chat API, MCP chat_turn tool, and rewrite frontend

feat: add Gemini backend (free tier LLM generation)

feat: dynamic MockBackend generates unique models from any prompt

feat: add NeuralCADBackend, vision support, and web demo frontend