chore(repo): remove personal RTK AGENTS.md from root (TASK-672) (#197)

AGENTS.md at repo root was personal RTK (Rust Token Killer) dev-tool
config — off-topic for the public repo. Delete it and add AGENTS.md to
.gitignore so contributors can keep a local copy without committing it.

Parent: PLAN-644.

.gitignore

@@ -39,6 +39,9 @@ Thumbs.db
 .codex
 .codex/
 
+# Agent tool local configs (not for public repo)
+AGENTS.md
+
 # Go
 *.test
 *.out

AGENTS.md

@@ -1,42 +0,0 @@
-<!-- headroom:rtk-instructions -->
-# RTK (Rust Token Killer) - Token-Optimized Commands
-
-When running shell commands, **always prefix with `rtk`**. This reduces context
-usage by 60-90% with zero behavior change. If rtk has no filter for a command,
-it passes through unchanged — so it is always safe to use.
-
-## Key Commands
-```bash
-# Git (59-80% savings)
-rtk git status          rtk git diff            rtk git log
-
-# Files & Search (60-75% savings)
-rtk ls <path>           rtk read <file>         rtk grep <pattern>
-rtk find <pattern>      rtk diff <file>
-
-# Test (90-99% savings) — shows failures only
-rtk pytest tests/       rtk cargo test          rtk test <cmd>
-
-# Build & Lint (80-90% savings) — shows errors only
-rtk tsc                 rtk lint                rtk cargo build
-rtk prettier --check    rtk mypy                rtk ruff check
-
-# Analysis (70-90% savings)
-rtk err <cmd>           rtk log <file>          rtk json <file>
-rtk summary <cmd>       rtk deps                rtk env
-
-# GitHub (26-87% savings)
-rtk gh pr view <n>      rtk gh run list         rtk gh issue list
-
-# Infrastructure (85% savings)
-rtk docker ps           rtk kubectl get         rtk docker logs <c>
-
-# Package managers (70-90% savings)
-rtk pip list            rtk pnpm install        rtk npm run <script>
-```
-
-## Rules
-- In command chains, prefix each segment: `rtk git add . && rtk git commit -m "msg"`
-- For debugging, use raw command without rtk prefix
-- `rtk proxy <cmd>` runs command without filtering but tracks usage
-<!-- /headroom:rtk-instructions -->