fix(ci): name master builds after the release they follow

Every non-tag build called itself 0.0.0-dev+<hash>, a placeholder that
said nothing about which release it came after and put a `+` in the
bundle's download URL. A master build now uses `git describe`, as a
local checkout already does: 2.0.0-3-g21746b1 is three commits past
2.0.0. The placeholder remains only for history that has no tag yet.

Three more things the tag path needed before its first run. The
forgejo-release action takes the notes text in `release-notes` and a
path in `release-notes-file`; the workflow passed a path to the former,
so the release body would have been the file name. The tag filter is
spelled with globs so it reads the same as a workflow pattern or a plain
glob. Python, used to extract the notes from the metainfo, was only in
the container as somebody else's dependency and is now listed. The
2.0.0 entry carries the date it is tagged on.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

packaging/flatpak/net.catcrafts.CrafterBuild.metainfo.xml

@@ -25,7 +25,7 @@
   </provides>
   <content_rating type="oars-1.1"/>
   <releases>
-    <release version="2.0.0" date="2026-10-02">
+    <release version="2.0.0" date="2026-10-03">
       <description>
         <p>First release distributed as a Flatpak, with a bundled LLVM 22 toolchain and WASI sysroot. Windows host support is removed; crafter-build gains --version and resolves its compiler from one place.</p>
       </description>