chore: remove exported/ from AGENTS.md, generalize binary ignores in .gitignore

- Removed non-existent exported/ directory from layout docs
- Replaced hardcoded bot binary entries with *_garage/out/ pattern for build directories
- Added all known bot binaries (GotoTest, OscillatorBot, PPO_Bot, QBot, SAC_LSTM_Bot)
  to .gitignore with clarifying comment about Nim's compilation target structure

Nim places compiled binaries at bot root (no extension) and in out/ subdirs.
The out/ pattern catches all build outputs; specific bot binaries listed for
root-level executables since gitignore lacks a reliable "no-extension files" glob.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -35,12 +35,6 @@ Single-context layout. See `docs/agents/domain.md`.
 - tools/ — generic tools valid for all bots (battle runners, scripts, etc.)
 - common_libs/ — shared libraries valid for all bots
 - worktrees/ — git worktrees (gitignored)
-- exported/ — sharable artifacts per bot
-  - botname/
-    - botname (binary)
-    - botname.json (metadata)
-    - botname.sh (linux/mac launcher)
-    - botname.cmd (windows launcher)
 - AGENTS.md
 - CONTEXT.md
 - README.md