Quickstart step 4 referenced scan_keys.js which doesn't exist in the
repo. Replace with find_all_keys_macos.c (Method A) and note Frida as
Method B requiring user's own script. Also add config.json note for
step 5.
- Zero out SQLite header offset 20 (reserved-space) after decryption,
otherwise SQLite miscalculates usable page size
- Add comment noting production code should verify HMAC on every page,
not just page 1