refactor: use Flaps CreateApp for app creation

[dangra]

Summary

• switch app creation paths from GraphQL CreateApp to Flaps CreateApp
• keep fly apps create --json compatible by refetching the full app before rendering
• simplify machine and postgres app-create helpers to return only the fields they actually use
• preserve existing launch output by adapting the Flaps response into the minimal app shape needed by callers

Testing

• go test ./...
• golangci-lint run

[Copilot]

Pull request overview

This PR refactors Fly app creation flows to use the Flaps API instead of the GraphQL-based CreateApp path, while preserving compatibility by refetching full app data where needed for rendering/output.

Changes:

• Switch app creation in machine run, launch, apps create, and postgres launcher paths from GraphQL to Flaps CreateApp.
• Wait for the newly created app via WaitForApp using the same Flaps client used to create it.
• Reduce the returned app/app-compact data to only the fields needed by the calling code, refetching full app details for JSON output where required.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
internal/command/machine/run.go	Uses Flaps to create ephemeral shell apps and machine-run apps; waits for app readiness and refetches compact app details when needed.
internal/command/launch/launch.go	Uses Flaps to create launch-plan apps and returns a minimal fly.App for follow-on printing/flow.
internal/command/apps/create.go	Uses Flaps to create apps; refetches full app via API client before JSON rendering to keep output compatible.
flypg/launcher.go	Uses Flaps to create postgres cluster apps and returns only required fly.AppCompact fields.

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