feat: configurable MAX_SESSIONS via N8N_MCP_MAX_SESSIONS env var (v2.28.3) (#468)

Make MAX_SESSIONS limit configurable for multi-tenant SaaS deployments.

- Add N8N_MCP_MAX_SESSIONS environment variable (default: 100)
- Include safety floor with Math.max(1, ...) to prevent invalid configs
- Update documentation in LIBRARY_USAGE.md, SESSION_PERSISTENCE.md
- Update CLAUDE.md and CHANGELOG.md

Fixes #468

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "n8n-mcp",
-  "version": "2.28.2",
+  "version": "2.28.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "n8n-mcp",
-      "version": "2.28.2",
+      "version": "2.28.3",
       "license": "MIT",
       "dependencies": {
         "@modelcontextprotocol/sdk": "1.20.1",