feat: config-driven architecture, install wizard, live runtime switching, usage tracking, auto-failover

Major changes:
- Config-driven adapters: all channels (Slack, Discord, Telegram, WebChat, Webhooks) controlled via config.json with enabled flags and token auto-detection, no CLI flags required
- Runtime engine field: runtime.engine selects opencode/claude from config
- Interactive install script: 8-phase setup wizard with AI runtime detection/installation, token setup, identity file personalization (personality presets), aetheel CLI command, background service (launchd/systemd)
- Live runtime switching: /engine, /model, /provider commands hot-swap the AI runtime from chat without restart, changes persisted to config.json
- Usage tracking: per-request cost extraction from Claude Code JSON output, cumulative stats via /usage command
- Auto-failover: rate limit detection on both runtimes, automatic switch to other engine on quota errors with user notification
- Chat commands work without / prefix (Slack intercepts / in channels), commands: engine, model, provider, config, usage, reload, cron, subagents, status, help
- /config set for editing config.json from chat with dotted key notation
- Security audit saved to docs/security-audit.md
- Full command reference in docs/commands.md
- Future changes doc with NanoClaw agent teams analysis
- Logo added to README and WebChat UI
- README fully rewritten with all features documented

.env.example

@@ -1,45 +1,23 @@
 # =============================================================================
-# Aetheel Configuration
+# Aetheel Secrets (.env)
 # =============================================================================
+# This file holds SECRETS ONLY (tokens, passwords, API keys).
+# All other configuration lives in ~/.aetheel/config.json.
+#
 # Copy this file to .env and fill in your values.
-# See docs/slack-setup.md and docs/opencode-setup.md for instructions.
 
-# --- Slack Tokens (required) ------------------------------------------------
-# Get these from https://api.slack.com/apps → your app settings
+# --- Slack Tokens ------------------------------------------------------------
 SLACK_BOT_TOKEN=xoxb-your-bot-token-here
 SLACK_APP_TOKEN=xapp-your-app-token-here
 
-# --- OpenCode Runtime (required for AI) -------------------------------------
-# Mode: "cli" (subprocess) or "sdk" (opencode serve API)
-OPENCODE_MODE=cli
+# --- Telegram Bot Token (optional) -------------------------------------------
+# TELEGRAM_BOT_TOKEN=your-telegram-bot-token-here
 
-# Model to use (optional — uses your OpenCode default if not set)
-# Examples:
-#   anthropic/claude-sonnet-4-20250514
-#   openai/gpt-5.1
-#   google/gemini-3-pro
-# OPENCODE_MODEL=
+# --- Discord Bot Token (optional) --------------------------------------------
+# DISCORD_BOT_TOKEN=your-discord-bot-token-here
 
-# CLI timeout in seconds (for CLI mode)
-OPENCODE_TIMEOUT=120
+# --- OpenCode Server Password (optional, SDK mode only) ----------------------
+# OPENCODE_SERVER_PASSWORD=your-server-password
 
-# Server URL for SDK mode (only needed if OPENCODE_MODE=sdk)
-# OPENCODE_SERVER_URL=http://localhost:4096
-# OPENCODE_SERVER_PASSWORD=
-
-# Working directory for OpenCode (optional — defaults to current directory)
-# OPENCODE_WORKSPACE=/path/to/your/project
-
-# --- Logging -----------------------------------------------------------------
-LOG_LEVEL=INFO
-
-# --- Claude Code Runtime (alternative to OpenCode) --------------------------
-# Use --claude flag to switch: python main.py --claude
-# CLAUDE_MODEL=claude-sonnet-4-20250514
-# CLAUDE_TIMEOUT=120
-# CLAUDE_MAX_TURNS=3
-# CLAUDE_NO_TOOLS=true
-
-# --- Memory System -----------------------------------------------------------
-# AETHEEL_WORKSPACE=~/.aetheel/workspace
-# AETHEEL_MEMORY_DB=~/.aetheel/memory.db
+# --- Anthropic API Key (optional, for Claude Code runtime) -------------------
+# ANTHROPIC_API_KEY=sk-ant-...