feat: v2.0.0 — on-demand spawning, session management, full tool access

Major architectural upgrade:
- Replace pool system with on-demand spawning (eliminates crash loops,
  DEGRADED states, and stdin timeout errors from v1.x)
- Add session management with --resume support (reduces token waste on
  multi-turn conversations)
- Expand default allowed tools (Bash, Read, Write, Edit, Glob, Grep,
  WebSearch, WebFetch, Agent) with configurable CLAUDE_ALLOWED_TOOLS
- Add system prompt pass-through (CLAUDE_SYSTEM_PROMPT)
- Add MCP config support (CLAUDE_MCP_CONFIG)
- Add concurrency control (CLAUDE_MAX_CONCURRENT, default 5)
- Add periodic auth health monitoring
- Add session API endpoints (GET/DELETE /sessions)
- Improve /health with full diagnostics (stats, sessions, errors, config)
- Fix timeout race condition (graceful SIGTERM → SIGKILL)
- Fix ERR_HTTP_HEADERS_SENT by checking headersSent in all response helpers
- Document coexistence with Claude Code interactive mode (Telegram, IDE)
- No conflict with CC: different ports, protocols, and process models

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "openclaw-claude-proxy",
-  "version": "1.8.0",
+  "version": "2.0.0",
   "description": "OpenAI-compatible proxy that routes requests through Claude CLI \u2014 use your Claude Pro/Max subscription as an OpenClaw model provider",
   "type": "module",
   "bin": {