docs: add V1 README, CHANGELOG, and package docs

Expand README with setup and API guidance, add CHANGELOG breaking
section, and refresh package documentation for the V1 API surface.

Co-authored-by: Cursor <cursoragent@cursor.com>

doc.go

@@ -3,12 +3,14 @@
 // # Module lifecycle
 //
 // Call [ModuleDB] once to register the database [app.Module], then use [SQLO]
-// to access the connection pool. Only one database per process is supported.
+// to access the connection pool. [CurrentDialect] reports the configured dialect.
+// Only one database per process is supported.
 //
 // # Query and mutation helpers
 //
 // [Fetch], [FetchOne], [Insert], [Update], [Delete], and their Must* and Context
 // variants wrap Jet [Statement] execution with consistent error semantics.
+// [WithTx] runs a function inside a SQL transaction.
 //
 // # Jet column utilities
 //
@@ -21,7 +23,11 @@
 // # Identifier types
 //
 // [StringKSUID] and [BinaryKSUID] wrap segmentio/ksuid with storage-specific
-// SQL encoding. [JSONB] provides map-based JSON column scanning.
+// SQL encoding. Both share identical GraphQL string transit. Choose StringKSUID
+// for text columns (VARCHAR, TEXT); choose BinaryKSUID for binary columns
+// (BINARY(20), BYTEA).
+//
+// [JSONB] provides map-based JSON column scanning for Postgres JSONB and MySQL JSON.
 //
 // # Pointer and string utilities
 //
@@ -31,7 +37,8 @@
 // # Debug logging
 //
 // Enable [DBConfig.DebugLog] and blank-import dbxm (MySQL) or dbxp (Postgres)
-// to register Jet query debug output.
+// to register Jet query debug output. Setup returns an error if DebugLog is
+// enabled without the matching blank import.
 //
 // # Dialect notes
 //