Port Express redirect response contracts

Context

The sequential Bun corpus frontier is js/third_party/express/res.redirect.test.ts at position 3967/4708, following Location handling in #224. This contributes to #66.

Acceptance criteria

• res.redirect(url) defaults to 302 and the status overload preserves explicit redirect codes.
• Redirect locations reuse URI-safe encoding and existing percent-octet preservation.
• HEAD suppresses response bodies.
• Accept negotiation returns safe text/HTML bodies or an empty body with correct headers and status reason.
• The copied suite passes with existing todos and is pinned in the permanent third-party gate.

Completed on main in ab75a32.

res.redirect() now supports default and explicit status codes, reuses percent-preserving Location encoding, emits canonical redirect reason text, negotiates safe HTML/text/empty responses from Accept, sets correct content metadata, and suppresses HEAD bodies without losing the computed length.

Verification: focused position 3967 reports files=1, passed=9, todo=4, failed=0, unsupported=0, allowed-empty=0; all permanent copied-corpus, SQL, and third-party gates pass.