isBase64 matched common field names like "name" — too loose for map
detection. Replace with isPronounceable which checks vowel/consonant
rhythm: real field names have natural syllable structure (15-80% vowels,
no 5+ consonant runs), while tokens and IDs don't.
Also fix allLookLikeIDs to reject keys that don't match any ID pattern
instead of silently accepting them.