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, 1 insertions, 2 deletions

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 402de0e..b58d10e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,7 +5,7 @@ on:
     branches: ["main"]
     paths-ignore:
       - "**.md"
-      - "ui/**"
+      - "packages/**"
   pull_request:
     branches: ["main"]
   workflow_dispatch:
@@ -78,7 +78,6 @@ jobs:
 
       - name: Install Frontend Dependencies
         if: github.event_name == 'workflow_dispatch'
-        working-directory: ./ui
         run: pnpm install
 
       - name: Install Tauri CLI