Bugfix: spacetime init --template react-ts creates a broken .env.local

[krisajenkins]

Description of Changes

Run spacetime init --template react-ts myproject and accept the defaults. You'll get a project path of myproject/ and a database name like myproject-30ctp. The "Next steps" instructions that follow, and the contents of the generated .env.local, use the wrong database name: they use the project name instead of the database you just confirmed. So out of the box, the client points at a database that doesn't exist.

This affects every built-in template with a TypeScript client, since they all share the same .env.local writer, and the spacetime publish line in "Next steps" was wrong for the Rust and C# templates too. It often goes unnoticed because spacetime dev overwrites .env.local on every build, but running the client directly shows it.

The database name prompt's answer only ever reached spacetime.local.json. It never made it into the template setup, so init_builtin wrote the env file from the project name:

write_typescript_client_env_file(project_path, &config.project_name, config.use_local)?;

The chosen database name is now passed from exec_init through init_from_template to init_builtin, and into print_next_steps. It's passed as a parameter rather than stored on TemplateConfig, because that struct is built in six places before the database name is known.

• Rename write_typescript_client_env_file's module_name parameter to db_name.
• Add a test that initialises the react-ts template offline with distinct project and database names, and asserts every *_SPACETIMEDB_DB_NAME in .env.local is the database name.

API and ABI breaking changes

None. Only private functions inside the CLI's init subcommand change signature.

Rollback safety impact

n/a

Expected complexity level and risk

1

Testing

• New test test_init_builtin_typescript_client_env_uses_database_name passes, and fails when the old &config.project_name argument is restored.
• cargo test -p spacetimedb-cli --lib subcommands::init::tests, cargo clippy -p spacetimedb-cli --tests and cargo fmt -p spacetimedb-cli -- --check are clean.
• Run spacetime init --template react-ts myproject, accept the defaults, and check that .env.local and the "Next steps" output both use the suffixed database name.