Switch to branch deployments in one-click deployments

[atharvadeosthale]

Ditches the release tag based deployments on one-click deployments, and rather uses branches instead. This means target repository doesn't need to have releases anymore.

Summary by CodeRabbit

• New Features

  • Branch-based deployments: detect branches from repo URLs, load/validate branches and add a branch selector in deploy flows.
  • Quick deploy via URL to create sites/functions and start deployments automatically.
  • Environment variable parsing supports KEY and KEY=VALUE pairs with prefilled values.

• Bug Fixes / Improvements

  • Default runtime updated to Node22; removed tag-based deployment paths in favor of branches.
  • Improved error handling, user notifications and billing/project-limit UI guards; payload now exposes parsed env vars.

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