feat(web/ui): consolidate dialogs, cards, and breakpoints (Pass 3)

- Unify modal/dialog system; .modal-* are now aliases of .dialog-*
- Migrate WorkspacesPage, start-tool-modal, merge-dialog, workspace-tools-panel to .dialog-*
- Add .card-sm/.card-md/.card-lg/.card-elevated/.card-borderless modifiers
- Apply card utilities across workspaces, projects, ssh-keys, workspace-detail, git-history
- Remove duplicated card-like background/border/padding from page CSS
- Remove 860px breakpoint; standardize on 767px/768px mobile split
- Add docs/development/ui-review-checklist.md
- Archive web-ui-spacing-typography-rework OpenSpec change

apps/web/src/components/features/project/ProjectCard.tsx

@@ -124,7 +124,7 @@ export const ProjectCard = ({
 					) : (
 						<div className="repo-list">
 							{(project.repositories || []).map((repo) => (
-								<div key={repo.id} className="repo-block">
+								<div key={repo.id} className="card card-md repo-block">
 									<div className="repo-header">
 										<h4>{repo.name}</h4>
 										<button