feat(ui): enable storybook snapshot tests

- adds a process-compose namespace for running `storybook` and `luakit` together to replicate the `webkit`-based rendering that happens inside of `webview`
- adds some helper scripts for running storybook tests and updating snapshots, with documentation in the README.
- adds a `clan-app-ui-storybook` package which builds and tests the storybook, checking for rendering changes

Currently, we’re only doing markup-based snapshot tests. We’re also using headless chromium for the tests by default as I couldn't get webkit to work in the nix build.

As we’re only markup-based for the time being, this should be ok. But eventually I'd like to get it working with webkit.

pkgs/clan-app/process-compose.yaml

@@ -1,7 +1,10 @@
 version: "0.5"
 
 processes:
+  # App Dev
+
   clan-app-ui:
+    namespace: "app"
     command: |
       cd $(git rev-parse --show-toplevel)/pkgs/clan-app/ui
       npm install
@@ -9,6 +12,7 @@ processes:
     ready_log_line: "VITE"
 
   clan-app:
+    namespace: "app"
     command: |
       cd $(git rev-parse --show-toplevel)/pkgs/clan-app
       ./bin/clan-app --debug --content-uri http://localhost:3000
@@ -17,3 +21,19 @@ processes:
         condition: "process_log_ready"
     is_foreground: true
     ready_log_line: "Debug mode enabled"
+
+  # Storybook Dev
+
+  storybook:
+    namespace: "storybook"
+    command: |
+      cd $(git rev-parse --show-toplevel)/pkgs/clan-app/ui
+      npm run storybook-dev -- --ci
+    ready_log_line: "started"
+
+  luakit:
+    namespace: "storybook"
+    command: "luakit http://localhost:6006"
+    depends_on:
+      storybook:
+        condition: "process_log_ready"