epic: reqstool architecture evolution

[jimisola]

Overview

Tracking issue for the architectural evolution of reqstool — from dict-based intermediate data structures to a queryable SQLite backend, improved output contracts, and editor integration.

Dependency order

Phase 1: Define the output contract

• feat: define JSON Schema for export and status command output #315 — feat: define JSON Schema for export and status command output
• epic: separate internal data layer from user-facing output contracts #318 — epic: separate internal data layer from user-facing output contracts

Phase 2: Core migration

• investigate: replace intermediate data structures with in-memory SQLite as single source of truth #313 — investigate: replace intermediate data structures with in-memory SQLite as single source of truth
• investigate: JSON export strategy with SQLite backend #317 — investigate: JSON export strategy with SQLite backend

Phase 4: Editor integration (depends on #313)

• feat: Language Server Protocol (LSP) for editor integration #314 — investigate: Language Server Protocol (LSP) for editor integration