* feat(github-app): App credentials, installation tokens, and a Select repo picker
RoboCo was 100% PAT-based. A singleton Fernet-encrypted github_app_credentials
row (migration 077, telegram-credentials pattern) now stores the App id +
private key; github_app_auth mints RS256 app JWTs and caches installation
tokens until 5 minutes before expiry. Projects can bind an installation
(projects.github_installation_id): get_decrypted_token returns a minted
installation token for bound projects and falls back to the stored PAT on
any minting failure, so all ten token consumers work unchanged.
CEO-gated routes expose credentials CRUD plus installation/repo listing, and
the New Project dialog gains a Select repo picker (disabled with a HelpTip
until the App is configured) that fills the git URL and binds the
installation; manual URL + PAT stays the default path.
* test(panel): mock the GitHub App credentials card in the settings page test
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Co-authored-by: Renn F <rennf93@users.noreply.github.com>
