chore: import upstream snapshot with attribution

examples/todo application (PostgreSQL)/sqlpage/migrations/0000_init.sql

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+create table
+    todos (
+        id serial primary key,
+        title text not null,
+        created_at timestamp default current_timestamp
+    );

examples/todo application (PostgreSQL)/sqlpage/migrations/README.md

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+# SQLPage migrations
+
+SQLPage migrations are SQL scripts that you can use to create or update the database schema.
+They are entirely optional: you can use SQLPage without them, and manage the database schema yourself with other tools.
+
+If you are new to SQL migrations, please read our [**introduction to database migrations**](https://sql-page.com/your-first-sql-website/migrations.sql).
+
+## Creating a migration
+
+To create a migration, create a file in the `sqlpage/migrations` directory with the following name:
+
+```
+<version>_<name>.sql
+```
+
+Where `<version>` is a number that represents the version of the migration, and `<name>` is a name for the migration.
+For example, `001_initial.sql` or `002_add_users.sql`.
+
+When you need to update the database schema, always create a **new** migration file with a new version number
+that is greater than the previous one.
+Use commands like `ALTER TABLE` to update the schema declaratively instead of modifying the existing `CREATE TABLE`
+statements.
+
+If you try to edit an existing migration, SQLPage will not run it again, will detect
+
+## Running migrations
+
+Migrations that need to be applied are run automatically when SQLPage starts.
+You need to restart SQLPage each time you create a new migration.
+
+## How does it work?
+
+SQLPage keeps track of the migrations that have been applied in a table called `_sqlx_migrations`.
+This table is created automatically when SQLPage starts for the first time, if you create migration files.
+If you don't create any migration files, SQLPage will never touch the database schema on its own.
+
+When SQLPage starts, it checks the `_sqlx_migrations` table to see which migrations have been applied.
+It checks the `sqlpage/migrations` directory to see which migrations are available.
+If the checksum of a migration file is different from the checksum of the migration that has been applied,
+SQLPage will return an error and refuse to start.
+If you end up in this situation, you can remove the `_sqlx_migrations` table: all your old migrations will be reapplied, and SQLPage will start again.

examples/todo application (PostgreSQL)/sqlpage/templates/README.md

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+# SQLPage component templates
+
+SQLPage templates are handlebars[^1] files that are used to render the results of SQL queries.
+
+[^1]: https://handlebarsjs.com/
+
+## Default components
+
+SQLPage comes with a set of default[^2] components that you can use without having to write any code.
+These are documented on https://sql-page.com/components.sql
+
+## Custom components
+
+You can [write your own component templates](https://sql-page.com/custom_components.sql)
+and place them in the `sqlpage/templates` directory.
+To override a default component, create a file with the same name as the default component.
+If you want to start from an existing component, you can copy it from the `sqlpage/templates` directory
+in the SQLPage source code[^2].
+
+[^2]: A simple component to start from: https://github.com/sqlpage/SQLPage/blob/main/sqlpage/templates/code.handlebars