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

omp-docs/pi/index.md

@@ -47,13 +47,15 @@ graph TD
 
 ## Note on the Live Default
 
-`models.json` defines the live provider set. The main session provider is
-`llamacpp`; the default model is `frank-default-large` (Dankclaw). Subagents
-default to the local provider with `subagents.defaultModel = frank-default-small`
-(Dankserver); larger roles map to `frank-default-large`. Two scopes own settings:
-the user `~/.pi/settings.json` (main → Dankclaw/large) and the project
-`/home/dank/.pi/agent/settings.json` (main → Dankserver/small). When the two
-disagree, the project-scope `settings.json` in the agent home wins for the agent's
-own main session; the user-scope file governs the interactive `pi` session.
+In the pi era, `models.json` defined the live provider set: the main session
+provider was `llamacpp` with default model `frank-default-large` (Dankclaw);
+subagents defaulted to `frank-default-small` (Dankserver); larger roles mapped
+to `frank-default-large`. Two scopes owned settings: the user
+`~/.pi/settings.json` (main → Dankclaw/large) and the project
+`/home/dank/.pi/agent/settings.json` (main → Dankserver/small); when they
+disagreed, the project-scope file won for the agent's own main session.
 
-> **Note:** This documentation describes the pi-coding-agent era. The system has since migrated to the OMP harness era. Configuration is now at `~/.omp/agent/config.yml` and `~/.omp/agent/models.yml` (imported from `~/.pi/agent/models.json`). Legacy `~/.pi/settings.json` and `~/.pi/agent/settings.json` remain as pi-era artifacts. New OMP-managed skills live in `~/.omp/agent/managed-skills/` alongside the legacy symlinked skills at `~/.pi/agent/skills/` → `~/.agents/skills/`.
+> **Note:** This documentation describes the pi-coding-agent harness (config
+> format, packages, skill system) as general reference material. The live
+> harness is OMP at `~/.omp/`; OMP-managed skills live in
+> `~/.omp/agent/managed-skills/`.