fix: improve mock backend conversation memory and history-aware responses

fix: Update mock ledger parser regex to prevent matching rupees as dates and support dynamic items (e.g. cotton)

docs: Update README with enhancements; implement GGUF latency fallback, KV cache thread-safety lock, mock structured parser, start-from-scratch reset, mobile CSS responsiveness, and nudge parser fixes

feat: migrate to custom SPA frontend on gr.Server with offline contacts, distress bypass, and onboarding tests

mock run working