agents: drop redundant agent-name headers from comments (+ fix self-trigger loop)

Gitea already attributes every comment/PR to its author, so the "🤖 **@name**" /
"🔨 **@name**" header at the top of agent comments was redundant noise. Remove it
everywhere and, in the process, close a self-trigger loop.

- publish.sh: post()/prpost() now append a hidden `<!-- 🤖 … -->` marker instead
  of each message carrying a visible "🤖 **@name**" header. The gate keys on the
  '🤖' char to skip agent replies, so the marker preserves loop-prevention while
  being invisible. All reply/status/autopilot strings drop the name header.
- route.sh: the "building on branch" notice is posted with the agent's PAT and
  previously had NO 🤖 marker + an "@name" mention, so it re-triggered the agent
  (the observed loop on issue #139). Reword without the self-name and add the
  hidden marker so it can't fire a new run.
- publish.sh: broaden the leading self-header stripper to drop any leading line
  referencing the agent's own @handle (e.g. "## 🔨 @senior — …"), not just bare
  "**@name**" lines. Legit headings like "## Summary" are preserved.
- run-agent.sh: tell the model not to begin its reply with its own name/handle.
- Trigger comments (delegation / autopilot / bounce) stay marker-free by design,
  so they still fire the next agent.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/scripts/run-agent.sh

@@ -102,6 +102,10 @@ PROMPT="You are @${NAME}, a member of an AI dev team working on this Gitea repos
    YOUR CAPABILITIES: model ${MODEL}. ${CAP}
    ${NOTE}
 
+   Your reply is posted as a comment already attributed to you (@${NAME}) — your name and avatar are
+   shown by Gitea. Do NOT begin your reply with your own name, an '@${NAME}' header, or a '🤖/🔨 @you'
+   line; just write the content directly.
+
    TEAM ROSTER (who does what — hand off if a task isn't yours):
    ${ROSTER}