feat: configurable MAX_SESSIONS via N8N_MCP_MAX_SESSIONS env var (v2.28.4) (#469)

* fix: n8n_test_workflow webhookId resolution and form handling (v2.28.2)

## Bug Fixes

- **webhookId Resolution**: Fixed trigger handlers using `node.id` instead of
  `node.webhookId` for building webhook URLs. This caused 404 errors when
  nodes had custom IDs.

- **Chat Trigger URL**: Fixed chat triggers using wrong URL pattern. Now
  correctly uses `/webhook/<webhookId>/chat` endpoint.

- **Form Content-Type**: Fixed form triggers failing with "Expected
  multipart/form-data" error by switching to proper multipart encoding.

## Enhancements

- **Form Field Types**: Added support for all n8n form field types (text,
  textarea, email, number, password, date, dropdown, checkbox, file, hidden)

- **Checkbox Arrays**: Automatically converts arrays to `field[]` format

- **Helpful Warnings**: Reports missing required fields with names and labels

- **Error Hints**: Provides complete field structure on failure

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>

* fix: address code review issues for form trigger improvements

- Add form-data as direct dependency (was only in devDependencies)
- Add TypeScript interfaces (FormFieldValue, FormFieldOption) replacing any types
- Add FORM_FIELD_TYPES constants for type-safe switch statements
- Add isValidBase64() validation for file uploads with size limits
- Add MAX_FILE_SIZE_BYTES (10MB) constant with validation
- Update form-handler.test.ts for FormData instead of JSON
- Update trigger-detector.test.ts for chat URL /chat suffix

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

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

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

* 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>

* fix: add QEMU setup for multi-arch Docker builds

Add docker/setup-qemu-action@v3 before Buildx setup to enable
proper QEMU emulation for linux/arm64 builds on GitHub Actions.

Fixes CI Docker build failure with "execve: No such file or directory"

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

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

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Romuald Członkowski <romualdczlonkowski@MacBook-Pro-Romuald.local>

CHANGELOG.md

@@ -7,6 +7,25 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.28.4] - 2025-12-05
+
+### Features
+
+**Configurable MAX_SESSIONS Limit (#468)**
+
+The `MAX_SESSIONS` limit is now configurable via the `N8N_MCP_MAX_SESSIONS` environment variable, addressing scalability issues for multi-tenant SaaS deployments.
+
+- **Problem**: Hardcoded limit of 100 concurrent sessions caused "Session limit reached" errors during peak usage
+- **Solution**: `MAX_SESSIONS` now reads from `N8N_MCP_MAX_SESSIONS` env var (default: 100)
+- **Usage**: Set `N8N_MCP_MAX_SESSIONS=1000` for higher capacity deployments
+- **Safety**: Includes `Math.max(1, ...)` floor to prevent invalid configurations
+- **Files**: `src/http-server-single-session.ts:44`
+
+```bash
+# Example: Allow up to 1000 concurrent sessions
+N8N_MCP_MAX_SESSIONS=1000
+```
+
 ## [2.28.3] - 2025-12-02
 
 ### Changed
@@ -596,7 +615,7 @@ Added export/restore functionality for MCP sessions to enable zero-downtime depl
 - `restoreSessionState(sessions)` method for session recovery
 - Validates session structure using existing `validateInstanceContext()`
 - Handles null/invalid sessions gracefully with warnings
-- Enforces MAX_SESSIONS limit (100 concurrent sessions)
+- Enforces MAX_SESSIONS limit (default 100, configurable via N8N_MCP_MAX_SESSIONS env var)
 - Skips expired sessions during restore
 
 **3. SessionState Type**