style(ui): refactor component styling and remove hand-drawn aesthetic

Refactor the frontend styling to use consistent design tokens and remove the hand-drawn/rotated aesthetic in favor of a cleaner, more standard UI.

- Replace hardcoded colors and border radii with CSS variables (e.g., `--default-border-color`, `--border-radius-lg`).
- Remove `transform: rotate(...)` and manual `box-shadow` offsets from various components (Sidebar, Dashboard, TemplatePicker, etc.).
- Update `Dashboard` to use a standard `ProgressBar` instead of a hand-drawn SVG chart.
- Standardize font families to use `--ui-font`.
- Clean up `TemplatePicker` logic to properly handle element grouping.
- Remove stale test result files and update `.last-run.json`.

frontend/test-results/.last-run.json

@@ -1,11 +1,4 @@
 {
   "status": "failed",
-  "failedTests": [
-    "c31ff144dc4fee3acd0a-bec551c658216ec9862a",
-    "c31ff144dc4fee3acd0a-f87315abf5d197970540",
-    "c31ff144dc4fee3acd0a-fc5e81ebcffdb7687b8e",
-    "c31ff144dc4fee3acd0a-989f5dcca4211fe0b2e4",
-    "c31ff144dc4fee3acd0a-ac5aa3cfe7537125a151",
-    "c31ff144dc4fee3acd0a-7f990aaafdc09c3794e8"
-  ]
+  "failedTests": []
 }