docs: trim badge row, advertise MOQT draft-18

[gmarzot]

Two independent README fixes.

Badge row width

GitHub emits the badges as a single inline <p> — verified against both the API render and the repo landing page payload. No <br>, and no rule in primer-*.css / github-*.css that would break the line. So the row is plain inline flow that wraps on width.

Summed intrinsic widths of the eight badge SVGs: 890px, plus seven inter-badge word-spaces ≈ 921px. The README column is ~920px — provable, since docs/banner.png is 5072px intrinsic and max-width:100% pins it to exactly the container width. The row had drifted onto the wrap threshold on its own: release widened with the version tag, issues gained a digit.

Dropping ci pr (~110px) brings it to ~810px with margin. ci main already covers build health; last commit is kept for the freshness signal.

MOQT draft version

The badge advertised draft-16. Per deps/moxygen/moxygen/MoQVersions.h:

constexpr std::array<uint64_t, 4> kSupportedVersions{
    kVersionDraft14, kVersionDraft15, kVersionDraft16, kVersionDraft18};

with kAlpnMoqtDraft18 = "moqt-18". Badge now reads draft-18.

Open question

This does not fully explain a report of the badges rendering one per line. Geometry says a 921px row in a 920px column wraps to two lines, not eight, and the stacking reproduced in incognito so it is not a browser extension. Landing this narrows the variable: if the row goes horizontal, it was width. If seven badges still stack, something is forcing breaks and needs a separate look.

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This change is 

[afrind]

I don't totally get what you are after here, but stamping to unblock

@afrind reviewed 1 file and all commit messages, and made 2 comments.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on gmarzot).

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-- commits line 9 at r1:
What is this saying? What is the badge even for?

[gmarzot]

-- commits line 9 at r1:

Previously, afrind wrote…

What is this saying? What is the badge even for?

saying that moqx supports the latest draft

[gmarzot]

there was some whacked thing where the badges were all stacked and looked like a mess... claude said the dimensions needed to be fiddled.. but also noticed draft-18 was not being advertised.. and useless pr ci status removed