[codex] harden muse digital store chat

[cxhihilwb123-hash]

Summary

• add realistic Muse digital store seed data and multi-turn simulation scripts
• harden AI chat reply sanitization for pricing, inventory, appointment, medical, and after-sales risk wording
• keep AI holding replies active during handoff until a human actually responds, so after-sales complaint flows do not go silent
• improve digital store setup/runtime behavior and support chat stability for commercial demo flows

Validation

• go test ./internal/ai/runtime ./internal/ai/runtime/workflow ./internal/services -run 'TestReplyEligibility|TestHandoffHolding|TestShouldSendHandoff|TestReplyCommit|TestSanitize|TestTailorDigitalStoreFallback|TestEnsureLowBudget|TestBuildAIReplyFailureFallback|TestUnderstandConversationMessage|TestWorkflowClarificationReply|TestWorkflowIdentityReply|TestExtractLeadInfo|TestSalesLeadExtract|TestDigitalStore|TestBuildDigitalStore|TestEnsure|TestSendAI|TestMessage' -count=1 -timeout 180s\n- pnpm --dir web typecheck\n- MUSE_MULTITURN_SCENARIOS=AFTER_SALES MUSE_MULTITURN_TURN_DELAY_MS=900 node scripts/run-muse-multiturn-simulation.mjs\n\n## Notes\nThe original repository denied direct push for the authenticated GitHub account, so this branch was pushed to the account fork and opened as a draft PR back to the upstream repository.