fix(ci): match release + forge-announce parsing to current yaml format

Both workflows looked for "**Hellion Chat <version>" as the changelog
subblock header, but the yaml convention is "**v<version> — <subtitle>"
(matches verify-changelog-sync.sh and the slim-rule grep). Plus the
indent-strip was 2 spaces, but prettier writes the changelog block with
4-space indent. Both regressions silently failed every release-workflow
run since the format change — likely why v1.4.3 was released manually.

Sync header marker to "**v$version " and indent-strip to 4 spaces in
both files.

.gitea/workflows/release.yml

@@ -111,20 +111,22 @@ jobs:
 
                   # changelog: is the last top-level key in the manifest, so
                   # everything after the marker is the literal block. Strip the
-                  # 2-space yaml indent from each line.
+                  # 4-space yaml indent (prettier convention) from each line.
                   $afterMarker = $raw.Substring($idx + $marker.Length)
                   $changelogBody = (($afterMarker -split "`r?`n") | ForEach-Object {
-                      if ($_ -match '^  ') { $_.Substring(2) } else { $_ }
+                      if ($_ -match '^    ') { $_.Substring(4) } else { $_ }
                   }) -join "`n"
 
-                  $header = "**Hellion Chat $version"
+                  # Subblock convention: "**vX.Y.Z — <subtitle> (<date>)**"
+                  # matches verify-changelog-sync.sh and slim-rule grep.
+                  $header = "**v$version "
                   $start = $changelogBody.IndexOf($header)
                   if ($start -lt 0) {
                       throw "No changelog entry for version $version found in $yamlPath. Update the changelog block before tagging a release."
                   }
 
                   $rest = $changelogBody.Substring($start)
-                  $nextHdr = $rest.IndexOf("`n`n**Hellion Chat ", 1)
+                  $nextHdr = $rest.IndexOf("`n`n**v", 1)
                   $trailer = $rest.IndexOf("`n`n---")
 
                   if ($nextHdr -ge 0 -and ($trailer -lt 0 -or $nextHdr -lt $trailer)) {