docs(pi): unify split package trees; move live OMP pages to core

Two directories documented one concept (pi npm packages): top-level
packages/ (browser-use, permission-system) and pi/packages/ (peon,
web-access, subagents). Merged into pi/packages/ — one row per package
in a single index, detail pages kept as archive records. The root
index's 'OMP packages and skills' section was doubly wrong (packages/
was pi, not OMP); it becomes a Skills tooling section pointing at the
consolidated /skills/ tree.

Moved the two LIVE omp pages out of the retired-harness banner:
pi/statusline.md -> core/statusline.md, pi/subagent-limits.md ->
core/subagent-limits.md (both document omp behavior against
agent/config.yml + the installed bundle; pi/index.md itself admitted
the mis-shelf). Retargeted every inbound link (core/index, system/
dankserver, log x2, pi/index, settings x2, moved files' own xrefs).

Refs #29

omp-docs/pi/packages/pi-permission-system.md

@@ -0,0 +1,37 @@
+---
+type: reference
+title: Pi Permission System
+description: Permission enforcement and policy configuration system for pi-coding-agent extensions.
+resource: https://github.com/gotgenes/pi-permission-system
+tags:
+  - pi
+  - package
+  - permissions
+  - unverified
+timestamp: 2026-08-28
+---
+[pi-permission-system](https://github.com/gotgenes/pi-permission-system) is the permission enforcement and policy configuration system for pi-coding-agent extensions.
+
+---
+
+## Documentation Index
+
+| Document | File | Description |
+|----------|------|-------------|
+| Overview | README.md | Package overview, install, quick start, feature list |
+| Configuration | configuration.md | Full policy reference, runtime knobs, per-agent overrides, common recipes |
+| Session Approvals | session-approvals.md | Session-scoped rules, pattern suggestions, bash arity table |
+| Cross-Extension API | cross-extension-api.md | Service accessor, event bus, decision/UI-prompt broadcasts |
+| Subagent Integration | subagent-integration.md | Permission forwarding, coexistence with subagent extensions |
+| Frontmatter Convention | permission-frontmatter-for-subagent-extensions.md | Convention guide for subagent extension authors |
+| OpenCode Compatibility | opencode-compatibility.md | Shared concepts, divergences, porting guide |
+| Troubleshooting | troubleshooting.md | Common issues, diagnostic logging, threat model |
+| Migration: Legacy → Flat | legacy-to-flat.md | Migration from pre-v2 config layout |
+| Migration: Strict Validation | strict-config-validation.md | Strict config validation (breaking) — reading and fixing rejected configs |
+
+---
+
+## Cross-References
+
+- See [Skills](/skills/index.md) for the skill toolchain that replaced pi-package distribution.
+- See [AGENTS.md Format](/core/agents-md-format.md) for the system-level instruction format that governs how this system is referenced in agent contracts.