kb: retire pi-installation association (OMP is the primary harness)

Purge live-state claims that ~/.pi is our harness; keep general
pi documentation in omp-docs/ and dated historical records.

- README.md: single config source; Legacy Notes reworded
- AGENTS.md: drop 'like ~/.pi did' framing
- APPEND_SYSTEM.md: okf-spec -> omp-docs/references/okf-spec.md
- dotfiles/zsh/.zshrc: systemprompt alias -> APPEND_SYSTEM.md
- managed skill llm-fleet-model-swap + model_config_sync skill:
  single-source models.yml; validation script YAML-only
- memories (MEMORY.md, memory_summary.md, learned.md): single source
- omp-docs: .okf root -> ~/.omp/omp-docs; de-live pi-era claims in
  pi/index.md, pi-web-access.md, engineering/agents-files.md

agent/memories/--home-dank-.omp--/memory_summary.md

@@ -1,4 +1,4 @@
 Current environment: `~/.omp` repo (main/develop), CachyOS + niri/Wayland + noctalia v5 (TOML-only, native). Desktop lock uses D-Bus msg; keybinds use v5 verbs; cursor is capitaine-cursors 48px. NPU deadlock fixed via nvidia-workarounds.conf.
-AI Config: `~/.omp/agent/models.yml` & `~/.pi/agent/models.json` are locked. Edit both. Context uses Ki (200k=204800). Providers: `llamacpp dankserver` (frank-default-small, 204800 ctx) & `llamacpp dankclaw` (frank-default-large Qwen3.8, 262144 ctx, ngram-mod). NPU `gemma4-it:e4b` on :7771 rejects WebP.
+AI Config: `~/.omp/agent/models.yml` is the single model registry (no second copy). Context uses Ki (200k=204800). Providers: `llamacpp dankserver` (frank-default-small, 204800 ctx) & `llamacpp dankclaw` (frank-default-large Qwen3.8, 262144 ctx, ngram-mod). NPU `gemma4-it:e4b` on :7771 rejects WebP.
 Git: Stash before checkout when `agent/memories/` is dirty. Deploy via `deploy.sh` (stow, sync mode). GITEA_TOKEN in `~/.config/environment.d/secrets.env`. OMP migration complete: use `APPEND_SYSTEM.md`, `task` tool, auto-discovered skills.
 Prioritize repo-tracked paths. v5 legacy v4 JSONs are inert.