feat(l1): add full-sync flag to server runner

[MegaRedHand]

This PR adds a way to enable full-sync in the server runner.

[Copilot]

Pull Request Overview

This PR replaces the --snap flag with a --full-sync flag in the server runner to enable full-sync mode instead of snap sync mode.

Key Changes

• Replaced --snap argument with --full-sync in the argument parser
• Updated variable handling to use FULL_SYNC instead of SNAP
• Modified Makefile to use --syncmode full instead of --syncmode snap

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tooling/sync/server_runner.py	Updates argument parser and variable handling to use full-sync flag
tooling/sync/Makefile	Updates documentation and sync command to use full-sync mode

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