Embed fonts into the executable, ship release artifacts as bare binaries

Fonts are now baked in with #load and loaded via LoadFontFromMemory
instead of LoadFontEx reading assets/*.ttf from disk, so a build no
longer needs an assets/ folder next to it at runtime - the chdir to
the executable's own directory in main.odin is dead code, removed.

just package / just package-windows now produce a single executable
(build/<name>_<version>_<os>_<arch>[.exe]) instead of a tar.gz/zip,
and the release workflow's upload/release-asset globs and the lld/zip
toolchain package list are updated to match.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/gitea-build.yaml

@@ -49,7 +49,7 @@ jobs:
       - name: Setup Toolchain
         uses: ./.gitea/actions/setup
         with:
-          packages: lld zip
+          packages: lld
 
       - name: Cache Windows SDK
         uses: actions/cache@v4