feat: Update testnet/mainnet config

[vukomir]

• Update testnet/mainnet config
• removed dev environment

[Copilot]

Pull request overview

Updates the bundled Docker bootstrap configuration for mainnet/testnet and removes the previously bundled dev environment to align supported deployments with mainnet/testnet only.

Changes:

• Enable relay_chain_light_client: true in both mainnet and testnet configs.
• Remove snapshot_url entries from relay chain config for mainnet/testnet.
• Remove docker/config/dev.yml and update README to reflect supported ENVIRONMENT values.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 1 comment.

File	Description
docker/config/testnet.yml	Enables relay-chain light client mode and removes relay snapshot configuration.
docker/config/mainnet.yml	Enables relay-chain light client mode and removes relay snapshot configuration.
docker/config/dev.yml	Removes dev environment bootstrap config.
README.md	Updates documentation to remove dev from supported ENVIRONMENT values (plus minor pruning text edit).

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[Copilot]

The pruning paragraph has a stray semicolon before the closing parenthesis ("mainnet and testnet;)") which reads like a typo. Please remove the semicolon so the sentence is grammatically correct.

Suggested change

	`blocks_pruning` and `state_pruning` are set in the bundled YAML per environment (for example `archive-canonical` for blocks and `256` for state on mainnet and testnet;). They are not controlled by separate container environment variables. To change pruning, use a custom configuration and adjust how you invoke the container, or extend or rebuild the image.
	`blocks_pruning` and `state_pruning` are set in the bundled YAML per environment (for example `archive-canonical` for blocks and `256` for state on mainnet and testnet). They are not controlled by separate container environment variables. To change pruning, use a custom configuration and adjust how you invoke the container, or extend or rebuild the image.