Preserve existing config when updating apps and static sites

Previously, updating an app or static site without specifying all flags
would clear existing configuration (e.g., custom domains would be lost
if --domain wasn't provided on update).

Now all config is merged in runDeploy before calling deploy functions:
- Load state once instead of 2-3 times
- Check for existing app once to determine create vs update
- Build merged DeployOptions with existing config + CLI overrides
- Deploy functions receive fully-merged config and just execute

This ensures existing configuration is preserved unless explicitly
overridden by CLI flags.

0 files changed, 0 insertions, 0 deletions