feat(landing): add strict ESLint + Prettier with pre-commit hooks (#50)

- Install ESLint 9 with flat config, TypeScript, Vue plugins
- Configure Prettier (140 char, 2-space indent, single quotes)
- Add pre-commit hooks via husky + lint-staged for auto-fix
- Rename components to multi-word (Countdown → CountdownTimer, etc.)
- Add explicit TypeScript prop/emit interfaces
- Remove all console.log statements
- Fix all ESLint violations and type errors
- Verify type-check, build, and HMR working

resolves #43

Co-authored-by: johba <johba@harb.eth>
Reviewed-on: https://codeberg.org/johba/harb/pulls/50

landing/package.json

@@ -9,7 +9,12 @@
     "preview": "vite preview",
     "build-only": "vite build",
     "type-check": "vue-tsc --build",
-    "subtree": "git subtree push --prefix dist origin gh-pages"
+    "subtree": "git subtree push --prefix dist origin gh-pages",
+    "lint": "eslint .",
+    "lint:fix": "eslint . --fix",
+    "format": "prettier --write \"src/**/*.{vue,ts,scss}\"",
+    "format:check": "prettier --check \"src/**/*.{vue,ts,scss}\"",
+    "prepare": "husky"
   },
   "dependencies": {
     "sass": "^1.83.4",
@@ -19,13 +24,22 @@
   "devDependencies": {
     "@tsconfig/node22": "^22.0.0",
     "@types/node": "^22.10.7",
+    "@typescript-eslint/eslint-plugin": "^8.45.0",
+    "@typescript-eslint/parser": "^8.45.0",
     "@vitejs/plugin-vue": "^5.2.1",
+    "@vue/eslint-config-typescript": "^14.6.0",
     "@vue/tsconfig": "^0.7.0",
+    "eslint": "^9.36.0",
+    "eslint-config-prettier": "^10.1.8",
+    "eslint-plugin-vue": "^10.5.0",
+    "gh-pages": "^6.1.1",
+    "husky": "^9.1.7",
+    "lint-staged": "^16.2.3",
     "npm-run-all2": "^7.0.2",
+    "prettier": "^3.6.2",
     "typescript": "~5.7.3",
     "vite": "^6.0.11",
     "vite-plugin-vue-devtools": "^7.7.0",
-    "vue-tsc": "^2.2.0",
-    "gh-pages": "^6.1.1"
+    "vue-tsc": "^2.2.0"
   }
 }