chore: remove tessl-managed agent config

Remove .codex/ and .gemini/ directories and the auto-generated tessl
section from CLAUDE.md.

Author: KRRT7

.codex/config.toml

@@ -30,11 +30,3 @@ Follow these steps in order, do not skip ahead:
 5. Never jump straight to writing a fix yourself — always go through steps 1-4
 
 Everything that can be tested should have tests.
-
-<!-- Section below is auto-generated by `tessl install` - do not edit manually -->
-
-# Agent Rules <!-- tessl-managed -->
-
-@.tessl/RULES.md follow the [instructions](.tessl/RULES.md)
-
-@AGENTS.md