fix: tea_relabel uses edit subcommand, add sha256 checksum for tea binary (#666)

- tea_relabel: use `tea issues edit` instead of `tea issues labels`
  (the latter is the list subcommand and ignores --labels)
- Dockerfile: verify tea binary sha256 after download

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/agents/Dockerfile

@@ -5,7 +5,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && rm -rf /var/lib/apt/lists/*
 
 # tea CLI — official Gitea/Forgejo CLI for issue/label/comment operations
+# Checksum from https://dl.gitea.com/tea/0.9.2/tea-0.9.2-linux-amd64.sha256
 RUN curl -sL https://dl.gitea.com/tea/0.9.2/tea-0.9.2-linux-amd64 -o /usr/local/bin/tea \
+    && echo "be10cdf9a619e3c0f121df874960ed19b53e62d1c7036cf60313a28b5227d54d  /usr/local/bin/tea" | sha256sum -c - \
     && chmod +x /usr/local/bin/tea
 
 # Claude CLI is mounted from the host via docker-compose volume.

lib/tea-helpers.sh

@@ -55,7 +55,7 @@ tea_relabel() {
   local IFS=','
   local labels="$*"
 
-  tea issues labels "$issue_num" --login "$TEA_LOGIN" --repo "$FORGE_REPO" \
+  tea issues edit "$issue_num" --login "$TEA_LOGIN" --repo "$FORGE_REPO" \
     --labels "$labels"
 }