fix(vt): keep OSC 8 hyperlinks when the URL contains semicolons

[youdie006]

Summary

Fixes #937.

An OSC 8 hyperlink is silently dropped when its URI contains a semicolon (for example https://example.com/f?a=1;b=2). The link text still renders, but the cells are never given the hyperlink, so it is not clickable.

Root cause

handleHyperlink in vt/osc.go split the payload on every semicolon:

parts := bytes.Split(data, []byte{';'})
if len(parts) != 3 || cmd != 8 { return }

The OSC 8 wire format is 8 ; params ; uri, where only the first two semicolons are field separators -- any later semicolon belongs to the URI. A URI with a semicolon produces four or more parts, so the len(parts) != 3 guard rejects the whole command and the link is discarded.

Fix

Split on only the first two semicolons with bytes.SplitN(data, ';', 3), so the remainder (the URI) keeps its own semicolons. The len(parts) != 3 guard still rejects malformed payloads with fewer than two semicolons, and the reset sequence (8;;) and ordinary links are unaffected.

This is orthogonal to #868: that PR corrects which slot the params and URI are stored in (they are currently exchanged), while this PR fixes the parser dropping semicolon URIs entirely. The two changes compose -- the field mapping is left to #868. The added test asserts the URI survives in either Link.URL or Link.Params, so it passes independently of #868's merge order.

Test

TestHyperlinkURLWithSemicolon drives Emulator.Write with the issue's reproduction and asserts the semicolon URI reaches the cells' link.

• RED (before fix): link dropped, Link.URL/Link.Params both empty -- FAIL.
• GREEN (after fix): URI present -- PASS.

Full vt suite passes; gofmt and go vet clean.

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AI-assisted: this change was prepared with the help of an AI coding assistant and reviewed by me.