fix(frontend): enforce lint locally and in CI, fix all pre-existing violations

## Pre-commit hook
- Add .husky/pre-commit at repo root: runs `cd frontend && npm run lint`
- Update prepare script in package.json to auto-configure git hooks path
  on npm install (git -C .. config core.hooksPath .husky)
- Add lint step to CI unit-tests job so it catches issues before tests run
- Add generated dirs to .prettierignore (paraglide_bak*, test-results, .auth)
- Add src/lib/paraglide_bak* to .gitignore so ESLint can ignore them

## ESLint fixes (all pre-existing)
- Disable svelte/no-navigation-without-resolve: false positive in SvelteKit
  (rule targets Svelte 5 standalone routing, not SvelteKit <a href>)
- Fix svelte/require-each-key: add (item.id)/(item) keys to all {#each} blocks
  across 10 files — improves Svelte reconciliation performance
- Fix svelte/prefer-writable-derived in PersonTypeahead: $state+$effect → $derived
- Fix svelte/prefer-svelte-reactivity: URLSearchParams → SvelteURLSearchParams,
  Map → SvelteMap (enables Svelte reactive tracking)
- Fix @typescript-eslint/no-unused-vars: remove dead imports/variables

## Prettier
- Run npm run format to bring all source files in line with .prettierrc

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/tailwind.config.js

@@ -1,25 +1,25 @@
 /** @type {import('tailwindcss').Config} */
 export default {
-  content: ['./src/**/*.{html,js,svelte,ts}'],
-  theme: {
-    extend: {
-      colors: {
-        brand: {
-          navy: '#002850',      // Header & Hero background
-          mint: '#A6DAD8',      // The Comma accent color
-          sand: '#E4E2D7',      // Content background
-          white: '#ffffff',
-        }
-      },
-      fontFamily: {
-        // Montserrat for UI/Headers, Merriweather for Body text (as established previously)
-        sans: ['Montserrat', 'sans-serif'],
-        serif: ['Merriweather', 'serif'],
-      },
-      fontSize: {
-        'huge': '4rem', // For the large stats numbers (e.g., "29", "5000+")
-      }
-    }
-  },
-  plugins: []
+	content: ['./src/**/*.{html,js,svelte,ts}'],
+	theme: {
+		extend: {
+			colors: {
+				brand: {
+					navy: '#002850', // Header & Hero background
+					mint: '#A6DAD8', // The Comma accent color
+					sand: '#E4E2D7', // Content background
+					white: '#ffffff'
+				}
+			},
+			fontFamily: {
+				// Montserrat for UI/Headers, Merriweather for Body text (as established previously)
+				sans: ['Montserrat', 'sans-serif'],
+				serif: ['Merriweather', 'serif']
+			},
+			fontSize: {
+				huge: '4rem' // For the large stats numbers (e.g., "29", "5000+")
+			}
+		}
+	},
+	plugins: []
 };