Add Playwright e2e coverage + comment-level video upload workflow (#40)

## Summary
- add Playwright e2e auth setup + seeded test DB flow
- fix Playwright startup order so DB seed runs before web server uses SQLite
- add full trip-planning e2e scenario (future trip, travellers, destination, flight, lodging, upcoming verification)
- configure Auth.js custom sign-in page for base-path routing
- add repo guidance in AGENTS.md / CLAUDE.md requiring e2e for user-facing changes
- document and validate comment-level Gitea video attachment workflow (create comment, upload to comment assets endpoint)

## Validation
- bunx playwright test e2e/auth.test.ts --project=chromium\n- bunx playwright test e2e/trip-planning.test.ts --project=chromium
- PW_VIDEO_MODE=on PW_TRACE_MODE=off bunx playwright test e2e/trip-planning.test.ts --project=chromium

## Issue
- relates to #38

Co-authored-by: AI Agent <ai-agent@campbellwireless.net>
Reviewed-on: #40
Co-authored-by: Shaun Campbell <shaun@campbellwireless.net>
Co-committed-by: Shaun Campbell <shaun@campbellwireless.net>

playwright.config.ts

@@ -0,0 +1,53 @@
+import { defineConfig, devices } from '@playwright/test';
+import { config as dotenvConfig } from 'dotenv';
+import { resolve } from 'path';
+
+// Load .env.test so both this process and the webServer child process see the values.
+dotenvConfig({ path: resolve(process.cwd(), '.env.test'), override: true });
+
+export default defineConfig({
+	testDir: './e2e',
+	fullyParallel: false,
+	forbidOnly: !!process.env.CI,
+	retries: process.env.CI ? 1 : 0,
+	workers: 1,
+	reporter: 'html',
+
+	use: {
+		baseURL: 'http://127.0.0.1:5173',
+		trace: process.env.PW_TRACE_MODE ?? 'on-first-retry',
+		video: process.env.PW_VIDEO_MODE ?? 'off'
+	},
+
+	projects: [
+		{
+			name: 'chromium',
+			use: { ...devices['Desktop Chrome'] }
+		}
+	],
+
+	globalTeardown: './e2e/setup/global-teardown.ts',
+
+	webServer: {
+		// Playwright starts webServer before globalSetup. Seed first so the app
+		// process opens the final DB file and never sees it replaced underneath.
+		command: 'bun run e2e/setup/seed-db.ts && bunx --bun vite dev --host 127.0.0.1',
+		url: 'http://127.0.0.1:5173/trips',
+		// Always start a fresh server to ensure it uses trips.test.db
+		reuseExistingServer: false,
+		timeout: 120_000,
+		env: {
+			AUTH_URL: process.env.AUTH_URL!,
+			AUTH_SECRET: process.env.AUTH_SECRET!,
+			LOCAL_AUTH_ENABLED: process.env.LOCAL_AUTH_ENABLED!,
+			LOCAL_AUTH_ARGON2_MEMORY_KB: process.env.LOCAL_AUTH_ARGON2_MEMORY_KB!,
+			LOCAL_AUTH_ARGON2_TIME_COST: process.env.LOCAL_AUTH_ARGON2_TIME_COST!,
+			LOCAL_AUTH_ARGON2_PARALLELISM: process.env.LOCAL_AUTH_ARGON2_PARALLELISM!,
+			ADMIN_USER_IDS: process.env.ADMIN_USER_IDS!,
+			DATABASE_URL: process.env.DATABASE_URL!,
+			SYNOLOGY_ISSUER: process.env.SYNOLOGY_ISSUER!,
+			SYNOLOGY_CLIENT_ID: process.env.SYNOLOGY_CLIENT_ID!,
+			SYNOLOGY_CLIENT_SECRET: process.env.SYNOLOGY_CLIENT_SECRET!
+		}
+	}
+});