#JMAP Implement JMAP API backed by IndexedDB with schema and query support

[shadowbas]

Develop a JMAP-compatible API layer that uses IndexedDB as its storage backend, including schema definition and query capabilities.

• Define schema: object stores, indexes, and key paths
• Support filtering, sorting, and pagination using JMAP Query objects
• Reuse the JMAP Query → predicate function logic for local query evaluation #JMAP Convert JMAP Query object to JS predicate function #1734