feat: add clsx and tailwind-merge dependencies, enhance Kanban components

- Added `clsx` and `tailwind-merge` to `package.json` and `package-lock.json` for improved class management and utility merging.
- Updated `Column` and `TaskCard` components to utilize new UI components (`Card`, `Badge`) for a more cohesive design.
- Refactored styles in `Header` and Kanban components to align with the new design system.
- Marked several tasks as completed in `TODO.md` reflecting progress on UI enhancements.

package-lock.json

@@ -9,12 +9,14 @@
       "version": "0.1.0",
       "dependencies": {
         "@prisma/client": "^6.16.1",
+        "clsx": "^2.1.1",
         "date-fns": "^4.1.0",
         "next": "15.5.3",
         "prisma": "^6.16.1",
         "react": "19.1.0",
         "react-dom": "19.1.0",
-        "sqlite3": "^5.1.7"
+        "sqlite3": "^5.1.7",
+        "tailwind-merge": "^3.3.1"
       },
       "devDependencies": {
         "@eslint/eslintrc": "^3",
@@ -2717,6 +2719,15 @@
       "integrity": "sha512-IV3Ou0jSMzZrd3pZ48nLkT9DA7Ag1pnPzaiQhpW7c3RbcqqzvzzVu+L8gfqMp/8IM2MQtSiqaCxrrcfu8I8rMA==",
       "license": "MIT"
     },
+    "node_modules/clsx": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/clsx/-/clsx-2.1.1.tgz",
+      "integrity": "sha512-eYm0QWBtUrBWZWG0d386OGAw16Z995PiOVo2B7bjWSbHedGl5e0ZWaq65kOGgUSNesEIDkB9ISbTg/JK9dhCZA==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/color": {
       "version": "4.2.3",
       "resolved": "https://registry.npmjs.org/color/-/color-4.2.3.tgz",
@@ -7409,6 +7420,16 @@
         "url": "https://opencollective.com/synckit"
       }
     },
+    "node_modules/tailwind-merge": {
+      "version": "3.3.1",
+      "resolved": "https://registry.npmjs.org/tailwind-merge/-/tailwind-merge-3.3.1.tgz",
+      "integrity": "sha512-gBXpgUm/3rp1lMZZrM/w7D8GKqshif0zAymAhbCyIt8KMe+0v9DQ7cdYLR4FHH/cKpdTXb+A/tKKU3eolfsI+g==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/dcastil"
+      }
+    },
     "node_modules/tailwindcss": {
       "version": "4.1.13",
       "resolved": "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.1.13.tgz",