Should Prince Harry read Harry as a given name? (prince, princess, lord, lady are titles but not given-name titles) #519

All four words are in TITLES but not in GIVEN_NAME_TITLES, so a title-plus-one-word input folds the word into the family name by rules.md#H1:

parse("Prince Harry")      # title='Prince',   family='Harry'
parse("Princess Anne")     # title='Princess', family='Anne'
parse("Lord Byron")        # title='Lord',     family='Byron'
parse("Lady Diana")        # title='Lady',     family='Diana'
parse("Lady Gaga")         # title='Lady',     family='Gaga'
parse("Dame Judi")         # title='Dame',     given='Judi'     # dame IS a given-name title

The membership criterion (rules.md H Background) is how the title addresses: a title that precedes and addresses by the given name belongs, whether or not the tradition keeps family names. sir, dame, king, queen are in on that basis.

Where the criterion lands

• prince, princess: address by given name. "Prince Harry", "Prince Charles", "Princess Anne" are the royal forms and there is no surname reading of the word that follows. These look like straightforward additions, the same shape as king/queen.
• lord: mostly addresses by peerage or surname. "Lord Byron", "Lord Tennyson", "Lord Voldemort" name the family or the title, not the person. "Lord Chancellor" and "Lord Mayor" are compound titles that H3 already chains. Membership looks wrong here.
• lady: split. A peer's daughter is addressed by given name ("Lady Diana", "Lady Jane Grey"), a peer's or knight's wife by surname ("Lady Thatcher"). The set has no way to say "sometimes", which is the same reason venerable stayed out (titles.py comment on Renunciate honorifics (Swami, Guru, Baba) put the monastic name in last #346).

What membership changes and what it does not

Membership only decides which field the one remaining word lands in. It does not change whether the word is read as a title, so it cannot fix the given-name collision:

parse("Prince Fielder")    # title='Prince', family='Fielder'  — Prince is his given name (#348)
parse("Robert Prince")     # given='Robert', family='Prince'   — unchanged either way

Two sites read the set: H1's fold and P5's bound-given join licence. After #489 lands, a title run addresses by its last title, so Her Royal Highness Princess Anne would move from family Anne to given Anne with princess added. Corpus census today: Prince Charles is the only affected name; Lord ... names are compounds or the fork guard His Excellency Lord Duncan, which must keep family Duncan.

Proposal

Add prince and princess; leave lord out; decide lady by which usage dominates the inputs callers actually hand the parser (the same relative-frequency test the 2.3.0 suffix-acronym collisions used). Each addition is a classified behavior change against 1.4.0, which reads Prince Harry with family Harry.

Split out of the #489/#316 title-run bundle, where it came up as vocabulary scope rather than run mechanics.