Initial commit using sqlc for query generation.

Basic crud ops and join queries to use sqlc, more complex either from
scratch or with a query builder later.

sqlc.yml

@@ -0,0 +1,15 @@
+version: "2"
+sql:
+  - engine: "postgresql"
+    queries: "sql/queries.sql"
+    schema: "sql/schema.sql"
+    gen:
+      go:
+        # 'db' is a standard package name for database logic
+        package: "db"
+        out: "internal/db"
+        sql_package: "pgx/v5"
+        # Recommended for better Go code:
+        emit_json_tags: true
+        emit_interface: true
+        emit_exact_table_names: false