paintplus: vendor the app source and rename from EditmaskwithAI

Bring the full EditmaskwithAI application into the repo under paintplus/
(429 files) so the service is self-contained — the installer copies the
vendored source to ~/docker/paintplus/src instead of cloning at runtime.

Rename to PaintPlus (service + branding; app logic untouched):
- services/editmaskwithai.sh -> services/paintplus.sh (register_service
  paintplus, install_paintplus, ~/docker/paintplus, Caddy paintplus:8000,
  Authelia option preserved)
- container names -> paintplus across docker-compose*.yml; dev network
  -> paintplus-network
- browser <title> -> "PaintPlus - AI Image Editor"; README heading ->
  PaintPlus with upstream provenance note
- README utilities table: editmaskwithai -> paintplus

Backend/frontend code (help strings referencing the old container name,
the ai_photo_edit.db filename) is intentionally left as-is to avoid
touching application logic.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nb2vJ8W7bHKx1JXVvpCraH

paintplus/frontend/manifest-disabled.json

@@ -0,0 +1,41 @@
+{
+	"name": "miniPaint",
+	"short_name": "miniPaint",
+	"start_url": "/",
+	"display": "standalone",
+	"orientation": "landscape",
+	"background_color": "#666d6f",
+	"description": "miniPaint is free online image editor using HTML5.",
+	"icons": [
+		{
+			"src": "images/manifest/48x48.png",
+			"sizes": "48x48",
+			"type": "image/png"
+		},
+		{
+			"src": "images/manifest/72x72.png",
+			"sizes": "72x72",
+			"type": "image/png"
+		},
+		{
+			"src": "images/manifest/96x96.png",
+			"sizes": "96x96",
+			"type": "image/png"
+		},
+		{
+			"src": "images/manifest/144x144.png",
+			"sizes": "144x144",
+			"type": "image/png"
+		},
+		{
+			"src": "images/manifest/168x168.png",
+			"sizes": "168x168",
+			"type": "image/png"
+		},
+		{
+			"src": "images/manifest/192x192.png",
+			"sizes": "192x192",
+			"type": "image/png"
+		}
+	]
+}