docs(readme): broaden CCS runtime positioning

- reframe README and internal docs around CCS as a multi-provider,

  multi-runtime manager

- preserve protected README sections and add guidance to avoid

  Gemini and Antigravity as generic hero examples

- update architecture and product docs to use Codex- and

  Droid-oriented examples in generic flows

docs/system-architecture/index.md

@@ -8,7 +8,7 @@ High-level architecture overview for the CCS (Claude Code Switch) system.
 
 ## System Overview
 
-CCS is a CLI wrapper that enables seamless switching between multiple Claude accounts and alternative AI providers (GLM, Gemini, Codex, Kiro, GitHub Copilot, OpenRouter, Qwen, Kimi, DeepSeek). It now supports multiple CLI targets (Claude Code, Factory Droid, Codex CLI) for credential delivery.
+CCS is a multi-provider profile and runtime manager that enables seamless switching between multiple Claude accounts, alternative AI providers, and multiple CLI targets (Claude Code, Factory Droid, Codex CLI) for credential delivery.
 
 The system consists of two main components:
 

docs/system-architecture/provider-flows.md

@@ -338,7 +338,7 @@ function selectBestAccount(accounts: AccountInfo[]): AccountInfo | null {
 |              OAuth - Authorization Code Flow (Port-based)                 |
 +===========================================================================+
 
-  1. User runs: ccs gemini
+  1. User runs: ccs codex
         |
         v
   2. Check token cache (~/.ccs/cliproxy/auth/)

docs/system-architecture/target-adapters.md

@@ -248,7 +248,7 @@ export WEBSEARCH_HOOK_ENV=...  # Image analysis, websearch
 
 ```bash
 # Direct invocation
-ccs gemini
+ccs codex
 → claude "args..."
   with ANTHROPIC_BASE_URL, ANTHROPIC_AUTH_TOKEN set
 
@@ -368,8 +368,8 @@ export class DroidAdapter implements TargetAdapter {
 
 ```bash
 # Direct invocation
-ccs gemini
-→ droid -m custom:ccs-gemini "args..."
+ccs codex
+→ droid -m custom:ccs-codex "args..."
   (credentials loaded from ~/.factory/settings.json)
 
 # With --target override