ci(docs): fix lychee --exclude (regex, not glob)

"**/archive/**" was being passed as a regex via --exclude-path,
causing 'repetition operator missing expression' parse error.
lychee --exclude takes a regex pattern; use '/archive/' to match
any URL/path containing an archive segment.

.gitea/workflows/reusable-docs.yml

@@ -37,7 +37,10 @@ jobs:
       - name: Internal link check (lychee)
         uses: lycheeverse/lychee-action@v2
         with:
-          args: --offline --no-progress --include-fragments "**/*.md" --exclude-path "**/archive/**"
+          # First positional arg is the input glob (files to scan).
+          # --exclude is a regex (not glob), matched against URL/path strings.
+          # We exclude any path component named "archive".
+          args: --offline --no-progress --include-fragments "**/*.md" --exclude '/archive/'
           fail: true
 
       - name: README presence (root)