Save in-progress keysat integration and StartOS 0.4 work

Snapshot of the working tree before cleanup. Captures:
- Keysat licensing: server/license.js, /api/license/* endpoints in
  server/index.js, activation modal in public/index.html, embedded
  Ed25519 issuer key (assets/issuer.pub).
- StartOS 0.4 expansion: setApiKey action, version files v0.1.1
  through v0.1.15, file-models/config.json.ts, manifest updates.
- Self-hosted registry server (startos-registry/).
- Build/deploy scripts (bin/bump-version.sh, bin/deploy.sh, vendored
  yt-dlp binary), .gitignore, .deploy.env.example.
- Recent design docs (KEYSAT_INTEGRATION.md, UPGRADE-DESIGN.md) —
  retained here so they remain recoverable when removed in the
  follow-up cleanup commit.

startos-registry/README.md

@@ -0,0 +1,67 @@
+# StartOS Package Registry
+
+A minimal, self-hosted StartOS package registry implementing the [Start9 Marketplace Protocol](https://github.com/Start9Labs/registry/blob/master/marketplace_protocol.md).
+
+**Registry URL:** `https://registry.satsflows.com`
+
+## Directory Layout
+
+```
+startos-registry/
+  server.js              # The registry server (~250 lines of Node.js)
+  registry.json          # Registry name and categories
+  package.json           # Node.js dependencies
+  nginx.conf             # nginx reverse proxy config
+  startos-registry.service  # systemd unit file
+  packages/
+    youtube-summarizer/  # One directory per package
+      package.json       # Package metadata (version, description, etc.)
+      icon.png           # Package icon (PNG)
+      LICENSE            # License text
+      INSTRUCTIONS.md    # User-facing instructions
+      *.s9pk             # The actual package binary
+    another-package/     # Add more packages the same way
+      package.json
+      icon.png
+      ...
+  scripts/
+    setup-vps.sh         # One-time VPS setup (nginx, TLS, systemd)
+    publish.sh           # Upload new versions from your dev machine
+```
+
+## Adding a New Package
+
+1. Create a directory under `packages/` with your package ID as the name
+2. Create a `package.json` inside it (copy from an existing one as a template)
+3. Add `icon.png`, `LICENSE`, and `INSTRUCTIONS.md`
+4. Place the `.s9pk` file in the same directory
+5. Reload: `systemctl reload startos-registry`
+
+## Updating a Package
+
+1. Build a new `.s9pk` with the updated version
+2. Update `packages/<id>/package.json`: bump the `version` field and add release notes
+3. Replace the `.s9pk` file
+4. Reload: `systemctl reload startos-registry`
+
+Or use the publish script from your dev machine:
+```bash
+./scripts/publish.sh youtube-summarizer ./youtube-summarizer_x86_64.s9pk
+```
+
+## Version Format (Exver)
+
+StartOS 0.4.0 uses Extended Versioning: `<upstream>:<downstream>`
+
+- `0.1.0:0` = upstream v0.1.0, wrapper revision 0
+- `0.2.0:0` = new upstream version
+- `0.2.0:1` = same upstream, updated wrapper/metadata
+
+## How Users Add Your Registry
+
+On their StartOS device:
+1. Go to **Marketplace**
+2. Tap **Change** (or the registry selector)
+3. Tap **Add custom registry**
+4. Enter: `https://registry.satsflows.com`
+5. Your packages appear in their marketplace