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/pages/GitHistoryPage.tsx

@@ -107,7 +107,7 @@ export const GitHistoryPage = () => {
           {commits.map((commit) => (
             <div
               key={commit.hash}
-              className={`commit-item ${selectedCommit === commit.hash ? "selected" : ""}`}
+              className={`card card-sm commit-item ${selectedCommit === commit.hash ? "selected" : ""}`}
               onClick={() => void handleCommitClick(commit.hash)}
               role="button"
               tabIndex={0}
@@ -146,7 +146,7 @@ export const GitHistoryPage = () => {
         </div>
 
         {selectedCommit && (
-          <div className="commit-detail-panel">
+          <div className="card card-lg commit-detail-panel">
             <div className="detail-header">
               <h3>Commit Details</h3>
               <button className="ghost-button" onClick={handleCloseDetail} type="button">

apps/web/src/pages/WorkspacesPage.tsx

@@ -120,10 +120,10 @@ export function WorkspacesPage() {
 
 				{startWorkspace && (
 					<div
-						className="modal-overlay"
+						className="dialog-overlay"
 						onClick={() => setStartWorkspace(null)}
 					>
-						<div className="modal-content" onClick={(e) => e.stopPropagation()}>
+						<div className="dialog" onClick={(e) => e.stopPropagation()}>
 							<h3>Start Tool</h3>
 							<ToolStarter
 								workspace={startWorkspace}
@@ -202,8 +202,8 @@ export function WorkspacesPage() {
 			)}
 
 			{startWorkspace && (
-				<div className="modal-overlay" onClick={() => setStartWorkspace(null)}>
-					<div className="modal-content" onClick={(e) => e.stopPropagation()}>
+				<div className="dialog-overlay" onClick={() => setStartWorkspace(null)}>
+					<div className="dialog" onClick={(e) => e.stopPropagation()}>
 						<h3>Start Tool</h3>
 						<ToolStarter
 							workspace={startWorkspace}