Playbook Author picks a project on web and mobile

[bryantderosier]

Part of #412. Milestone: Squadron fold.

Outcome

Playbook Author settings pick a project instead of a Squadron, on web and mobile.

Scope

• Web: apps/web/src/j5/playbooks/PlaybookLibrarySettings.tsx.
• Mobile: apps/mobile/src/j5/playbooks/PlaybookLibrarySettingsScreen.tsx.
• Client-runtime: playbooks.ts drops playbookAuthorSquadrons and launches the author thread in the chosen project with no squadronId. Since feat(squadrons): a thread launched without a Squadron joins its project's Squadron #430, a launch without a Squadron joins its project's Squadron, so this slice doesn't need the ledger re-key and can land early.

Done when

• Starting Playbook Author from Settings works on web and mobile with a project picked. Each client gets one real-client pass.
• No playbook code reads SquadronDirectory.