fix(ci): absorb the v prefix a release dispatch is typed with

[florianmousseau]

The release workflow reads the version from a dispatch field and looks the
changelog section up by its heading, ## [1.8.11]. Typing the tag instead
of the version - v1.8.11 - makes it search for ## [v1.8.11], which
cannot exist, and the run fails on:

No changelog section for [v1.8.11].

That is the guard doing its job: it refuses to tag and publish a version
whose notes it cannot find. But the field asks for a bare number while the
thing everyone has in mind is the tag, so the mistake is a reflex, and it
costs a red run in the history of a public repository (it happened on
2026-07-30, fourteen seconds after release: 1.8.11 was merged).

The prefix is now absorbed once, in the step that already resolves the
target commit, and both later steps read the normalised value. The field
description says so instead of asking the reader to remember it.

Nothing else changes: a dispatch on 1.8.19 behaves exactly as before, and
the workflow stays idempotent on a version already released.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud