docs: update README and documentation to match current state (v2.5.1)

- Update n8n version from v1.97.1 to v1.99.1 in README
- Fix 7 broken documentation links to point to existing files
- Standardize Docker image size to ~280MB across all docs (was inconsistent: 150MB/200MB/283MB)
- Add missing npm scripts for test commands (test:essentials, test:enhanced-validation, etc.)
- Update CHANGELOG.md with missing versions 2.4.0 through 2.5.1
- Update README_CLAUDE_SETUP.md to list all 21+ MCP tools (was only showing 6)
- Document 5 additional npm scripts in CLAUDE.md
- Update AI-capable nodes count to 263 (was 35 in old docs)

All documentation now accurately reflects the current codebase state.

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

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

package.json

@@ -27,6 +27,10 @@
     "test:templates": "node dist/scripts/test-templates.js",
     "test:workflow-validation": "node dist/scripts/test-workflow-validation.js",
     "test:template-validation": "node dist/scripts/test-template-validation.js",
+    "test:essentials": "node dist/scripts/test-essentials.js",
+    "test:enhanced-validation": "node dist/scripts/test-enhanced-validation.js",
+    "test:ai-workflow-validation": "node dist/scripts/test-ai-workflow-validation.js",
+    "test:mcp-tools": "node dist/scripts/test-mcp-tools.js",
     "db:rebuild": "node dist/scripts/rebuild-database.js",
     "db:init": "node -e \"new (require('./dist/services/sqlite-storage-service').SQLiteStorageService)(); console.log('Database initialized')\"",
     "docs:rebuild": "ts-node src/scripts/rebuild-database.ts"