chore(ui): refactor workspace to monorepo (#70)

## Summary by Sourcery

Refactor the UI project structure into a pnpm monorepo packages layout
and align tooling and automation with the new paths.

Enhancements:
- Reorganize the UI app from the root ui directory into packages/ui
within a pnpm workspace.
- Update pnpm workspace configuration to include all packages under
packages/*.
- Adjust paths in changeset configuration so the @dropout/ui package
resolves from packages/ui.

Build:
- Update pre-commit configuration paths and arguments to reflect the new
UI location and normalize hook argument formatting.
- Update Dependabot configuration so npm updates target /packages/ui
instead of /ui.

CI:
- Update GitHub Actions workflows to watch packages/** instead of ui/**
and to run frontend tasks from packages/ui.
- Update pnpm cache dependency paths in workflows to use the root
pnpm-lock.yaml.
- Simplify frontend install steps in test workflows to run from the
repository root.

Chores:
- Add a new index.html under packages/ui and remove the old
ui/index.html to match the new project layout.

1 files changed, 4 insertions, 5 deletions

diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index b1e7254..d5bd131 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -4,7 +4,7 @@ on:
   push:
     branches: ["main", "dev"]
     paths:
-      - "ui/**"
+      - "packages/**"
   workflow_dispatch:
 
 permissions:
@@ -27,16 +27,15 @@ jobs:
         with:
           node-version: 22
           cache: "pnpm"
-          cache-dependency-path: "ui/pnpm-lock.yaml"
+          cache-dependency-path: "pnpm-lock.yaml"
 
       - run: pnpm install
-        working-directory: ui
 
       - run: pnpm format
-        working-directory: ui
+        working-directory: packages/ui
 
       - run: pnpm lint:fix
-        working-directory: ui
+        working-directory: packages/ui
 
       - name: Commit changes
         uses: stefanzweifel/git-auto-commit-action@v5