fix: accept Homebrew-interpolated final tag in cask URL verify

[rianjs]

Problem

The Confirm published cask URL pins the final tag step in release.yml greps the dist cask for a literal /download/<final-tag>/. But release-preflight intentionally lets bare-v repos omit url.template, and goreleaser then renders the cask URL as Homebrew interpolation — /download/v#{version}/ — not a literal tag. Even url.template repos commit the interpolated form to the tap.

So the literal grep only passed for casks that happened to bake a literal tag. The first bare-v repo to reach the new step — slck v3.1.58 — failed, and its homebrew/chocolatey/winget/linux-packages fan-out was skipped, leaving every distro channel a release behind (stuck at 3.1.51) even though the GitHub release published all binaries.

Fix

Accept either:

• the literal final tag — /download/v3.1.58/, or
• the final-tag prefix plus #{version} — /download/v#{version}/ (bare) or /download/jtk-v#{version}/ (prefixed).

Both forms genuinely pin the final tag; Homebrew resolves #{version} at install. The prefix is derived by stripping the version suffix from the final tag, so the guards are preserved:

• a prefixed repo (jtk-v) emitting a bare v#{version} still fails (wrong-prefix guard);
• a cask pinning an older version still fails (stale-tag guard).

Verified against all six cases (bare/prefixed × literal/interpolated, plus both guards).