feat(mvp): phase 8 - integration, testing & deployment

Fix all build/type/lint errors (zod 3.25 compat wrapper, Svelte 5 fixes),
write 115 unit tests across 10 test files, expand seed script with demo
data, update Docker config with migration on startup.

src/lib/server/services/authService.ts

@@ -37,7 +37,7 @@ export async function verifyPassword(password: string, hash: string): Promise<bo
 
 export function signAccessToken(payload: JwtPayload): string {
 	return jwt.sign(payload, getJwtSecret(), {
-		expiresIn: getJwtExpiry()
+		expiresIn: getJwtExpiry() as string & jwt.SignOptions['expiresIn']
 	});
 }