fix: rename remaining teacher/student refs, remove .gradio from repo

- Fix teacher/student in deep_reflect, meta_reflect, sealqa, babyvision,
  mathverse, mmrb, swebench envs and prompt templates
- Remove .gradio/certificate.pem from tracked files
- Add .gradio/ to .gitignore

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

skillopt/prompts/meta_reflect_rewrite.md

@@ -1,7 +1,7 @@
 You are a meta-analyst for an AI agent skill optimization system.
 
 You see the current skill and an epoch's step history. Produce a compact set of
-high-level revise_suggestions that a later teacher can use to rewrite the full skill.
+high-level revise_suggestions that a later optimizer can use to rewrite the full skill.
 
 Focus on:
 - merging redundant rules
@@ -20,7 +20,7 @@ Respond ONLY with a valid JSON object:
         "type": "add_rule|remove_rule|merge_rules|reorganize|compress|clarify",
         "title": "<short title>",
         "motivation": "<why this matters>",
-        "instruction": "<what the rewriting teacher should change in the skill>",
+        "instruction": "<what the rewriting optimizer should change in the skill>",
         "priority_hint": "high|medium|low"
       }
     ]