mergedrop: bump to 1.0.1, rebuild from vid-merger source; fix stale source repo URL in build.sh

- config.json: tipi_version 1->2, version 1.0.0->1.0.1, updated_at bumped;
  added missing required fields supported_architectures (["amd64"]) and
  dynamic_config (true) so the app passes schema validation
- docker-compose.json: main service image mergedrop:1.0.0 -> mergedrop:1.0.1
- build/build.sh: default IMAGE_TAG 1.0.0 -> 1.0.1; default SOURCE_REPO
  corrected from stale video-merger.git to vid-merger.git
- build/README.md: corrected source repo pointer from video-merger to
  vid-merger

Image git.alexzaw.dev/alexz/mergedrop:1.0.1 is being built from
git.alexzaw.dev/alexz/vid-merger @ 9b27376 in a separate process.
Deploy chain (appstore update / app update) to be run separately once the
image build completes.

apps/mergedrop/config.json

@@ -7,8 +7,10 @@
   "port": 8765,
   "id_name": "mergedrop",
   "description": "Self-hosted drag-and-drop video merger. Drop clips, reorder, and build a single MP4 with ffmpeg.",
-  "tipi_version": 1,
-  "version": "1.0.0",
+  "tipi_version": 2,
+  "version": "1.0.1",
+  "dynamic_config": true,
+  "supported_architectures": ["amd64"],
   "categories": ["media", "utilities"],
   "short_desc": "Drag, sort, merge — your videos into one MP4.",
   "author": "MergeDrop",
@@ -28,5 +30,6 @@
       "required": false,
       "env_variable": "MERGEDROP_MAX_FILE_SIZE"
     }
-  ]
+  ],
+  "updated_at": 1787292618234
 }