feat: add Schema tab with ERD visualization

Add a new Schema tab at /schema that displays an interactive Entity
Relationship Diagram showing database tables, columns, and foreign key
relationships using ReactFlow.

- Add @xyflow/react and dagre dependencies for diagram rendering
- Create ERD components (erd-diagram, table-node, use-layout hook)
- Add schema route with loader for ERD data
- Update navigation to include Schema tab in desktop and mobile views
- Add ReactFlow custom styles for controls, minimap, and edges

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: frectonz

flake.nix

@@ -55,7 +55,7 @@
           pname = "ui";
           version = "0.0.0";
           src = ./ui;
-          npmDepsHash = "sha256-1k054qLwvpSrWfBKXJRVVomCh1dMSEtjtwUTWCoAaEg=";
+          npmDepsHash = "sha256-tM3PLk9/H08YbNGNXM2bdnMNzBKlPxI4j4yTKoVTCzk=";
           installPhase = ''
             cp -pr --reflink=auto -- dist "$out/"
           '';

ui/package-lock.json

@@ -24,8 +24,10 @@
     "@tanstack/react-router": "^1.130.2",
     "@tanstack/react-table": "^8.21.3",
     "@uidotdev/usehooks": "^2.4.1",
+    "@xyflow/react": "^12.10.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "dagre": "^0.8.5",
     "lucide-react": "^0.533.0",
     "monaco-editor": "^0.52.2",
     "monaco-sql-languages": "^0.15.1",
@@ -46,6 +48,7 @@
     "@tanstack/react-query-devtools": "^5.83.0",
     "@tanstack/router-devtools": "^1.35.3",
     "@tanstack/router-plugin": "^1.130.2",
+    "@types/dagre": "^0.7.53",
     "@types/node": "^24.1.0",
     "@types/react": "^19.1.9",
     "@types/react-dom": "^19.1.7",