fix: add warnings for If/Switch node connection parameters (issue #360)

Implemented a warning system to guide users toward using smart parameters
(branch="true"/"false" for If nodes, case=N for Switch nodes) instead of
sourceIndex, which can lead to incorrect branch routing.

Changes:
- Added warnings property to WorkflowDiffResult interface
- Warnings generated when sourceIndex used with If/Switch nodes
- Enhanced tool documentation with CRITICAL pitfalls
- Added regression tests reproducing issue #360
- Version bump to 2.22.1

The branch parameter functionality works correctly - this fix adds helpful
warnings to prevent users from accidentally using the less intuitive
sourceIndex parameter.

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>

src/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.ts

@@ -272,6 +272,8 @@ Please choose a different name.
       'Use "updates" property for updateNode operations: {type: "updateNode", updates: {...}}',
       'Smart parameters (branch, case) only work with IF and Switch nodes - ignored for other node types',
       'Explicit sourceIndex overrides smart parameters (branch, case) if both provided',
+      '**CRITICAL**: For If nodes, ALWAYS use branch="true"/"false" instead of sourceIndex. Using sourceIndex=0 for multiple connections will put them ALL on the TRUE branch (main[0]), breaking your workflow logic!',
+      '**CRITICAL**: For Switch nodes, ALWAYS use case=N instead of sourceIndex. Using same sourceIndex for multiple connections will put them on the same case output.',
       'cleanStaleConnections removes ALL broken connections - cannot be selective',
       'replaceConnections overwrites entire connections object - all previous connections lost',
       '**Auto-sanitization behavior**: Binary operators (equals, contains) automatically have singleValue removed; unary operators (isEmpty, isNotEmpty) automatically get singleValue:true added',