feat(desktop): build apps in project folders (plan 66, Part D)

[MoSofi]

Part D of plan 66: the desktop app opens project folders and builds apps in them with the Designer.

What is in it

• Start, New app, Open a folder: the first screen, a new project made by the engine's own new with the npm the app carries, the recent list, the trust question before anything of a folder runs, and the opening road (a server that already has the folder, data from a newer Adminium, another manager's lockfile, an older pin, missing packages, data with no key, what was found or made, the accounts a folder came with).
• Versions: git found or offered as a download (hash-checked), versions coming on without a restart.
• Model keys kept by the app (safeStorage), handed to a project's server by message, never to its .env.
• Build | Share: a project is built on this computer only, or shared on the network with the Designer off; an owner password first; the kept port; the Shared page with its addresses and a QR code.
• Export as one ZIP, with or without the data and the key.
• Connect to another Adminium in a window of its own with none of the app's bridge.
• Release run: a starter lockfile carried in the app, the entitlement checked on the app and its helpers, the pinned engine asked of npm, and a smoke of the PACKED app on the three systems.
• Docs: "Build an app in the desktop app"; folder-facts and install --update in the CLI reference.

Checked here

• Unit suites green (server 7718, dashboard 3084, desktop 1188, the rest), coverage floors held; every preflight gate green. The full test step was run by parts: this machine was under load and one timing test at a time failed in the combined run, each passing alone.
• Desktop e2e: 42 passed, before and after merging main.
• The packed, signed app on macOS arm64: the packed smoke, and a walk of every new screen.
• A review of the whole diff; what it found is fixed in 4ff576ca, b393bf4b, 5775b5b1.

Not checked here

• Windows and Linux packed apps, the clean Mac (no developer tools), a real share to a phone, a real model, notarization: the owner's walks and the manual run of desktop-release.yml on this branch.
• Postgres and MySQL legs, VRT: CI.

Not to be merged before the owner's walks.

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