docs: add external documentation site content

Add structured documentation covering quickstart, architecture, core
concepts, API reference, adapter guides, CLI commands, deployment
options, and operator/developer guides.

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

docs/adapters/codex-local.md

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+---
+title: Codex Local
+summary: OpenAI Codex local adapter setup and configuration
+---
+
+# Codex Local Adapter
+
+The `codex_local` adapter runs OpenAI's Codex CLI locally. It supports session persistence via `previous_response_id` chaining and skills injection through the global Codex skills directory.
+
+## Prerequisites
+
+- Codex CLI installed (`codex` command available)
+- `OPENAI_API_KEY` set in the environment or agent config
+
+## Configuration Fields
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `cwd` | string | Yes | Working directory for the agent process |
+| `model` | string | No | Model to use |
+| `promptTemplate` | string | No | Prompt for resumed sessions |
+| `bootstrapPromptTemplate` | string | No | Prompt for first run |
+| `env` | object | No | Environment variables (supports secret refs) |
+| `timeoutSec` | number | No | Process timeout (0 = no timeout) |
+| `graceSec` | number | No | Grace period before force-kill |
+| `dangerouslyBypassApprovalsAndSandbox` | boolean | No | Skip safety checks (dev only) |
+
+## Session Persistence
+
+Codex uses `previous_response_id` for session continuity. The adapter serializes and restores this across heartbeats, allowing the agent to maintain conversation context.
+
+## Skills Injection
+
+The adapter symlinks Paperclip skills into the global Codex skills directory (`~/.codex/skills`). Existing user skills are not overwritten.
+
+## Environment Test
+
+The environment test checks:
+
+- Codex CLI is installed and accessible
+- Working directory exists and is valid
+- API key is configured