Apple AAT — Advanced Typography scaffolds

Scaffolds for the Apple AAT tables (RM06). The modules decode the envelopes (header, version, count, offsets) and, where the format allows it, the AAT lookup tables themselves; the state-machine bodies (morx subtable actions, kerx formats 1/2/4/6) are kept as raw bytes and are not decoded.

The stub-ness signal is not uniform across the six modules — verify against the live code rather than assuming a shared contract:

• prop.js and morx.js/kerx.js (non-format-0 kerx subtables) return parsed: false (prop.js also adds reason: 'aat-state-machine-deferred'); kerx.js format 0 subtables and any fully-decoded record return parsed: true.
• ankr.js and lcar.js give no runtime signal at all — their parseAnkr/parseLcar return an AAT lookup-table lookupFormat + raw lookupBytes, but neither module decodes the AAT lookup formats (0/2/4/6/8/10) needed to resolve a glyph ID to its anchor/caret block offset. There is no marker or parsed field to detect this in either file — a consumer must not call readAnchorBlock/readCaretBlock with an offset derived from the lookup table, since the table is not decoded.
• feat.js has no stub signal because it has no state-machine body to defer — parseFeat fully decodes every feature/setting record.