fix(robomp): parameterized bot identity in system prompts

system_append.md and system_append_pr_review.md hardcoded the literal
'robomp' as the bot persona, so the agent self-mentioned an account
that does not exist when deployments configure ROBOMP_BOT_LOGIN to a
different login. Affected users saw the agent ask for @robomp mentions
that GitHub never resolved to the actual bot.

Thread the configured login through persona.system_append and
persona.system_append_pr_review as a bot_login keyword, render it
via the existing {{bot_login}} placeholder, and pass
settings.bot_login at the worker callsite. Regression test asserts the
templated login lands in both prompts and the legacy literal is gone.

Fixes #1932

python/robomp/tests/test_persona.py

@@ -181,3 +181,27 @@ def test_review_completion_reminder_mentions_submit_only() -> None:
     )
     assert "submit_pr_review" in out
     assert "gh_open_pr" not in out
+
+
+def test_system_append_renders_configured_bot_login() -> None:
+    out = persona.system_append(
+        repo=_Repo(),
+        issue=_Issue(),
+        workspace=_Workspace(),
+        bot_login="Svitter",
+    )
+    # The hardcoded persona name MUST be replaced by the configured login so
+    # the agent self-mentions the account that actually receives webhooks.
+    assert "You are **@Svitter**" in out
+    assert "**robomp**" not in out
+
+
+def test_system_append_pr_review_renders_configured_bot_login() -> None:
+    out = persona.system_append_pr_review(
+        repo=_Repo(),
+        issue=_Issue(),
+        workspace=_Workspace(),
+        bot_login="Svitter",
+    )
+    assert "You are **@Svitter**" in out
+    assert "**robomp**" not in out