Extract shared SQLStore with Dialect interface for the ~5% that
differs between backends (DDL, placeholders, sequence resets).
- New dialect.go: Dialect interface + placeholder rewriter (? → $N)
- New sqlstore.go: single implementation of all 19 Store methods
- sqlite.go: reduced from 286 to 83 lines (SQLiteDialect only)
- postgres.go: reduced from 266 to 78 lines (PostgresDialect only)
- main.go: use NewSQLiteStore/NewPostgresStore constructors
Zero CRUD logic duplication. Every future schema change written once.
lerko
ab75f61c6b