fix: resolve release workflow YAML parsing errors with script-based approach

Replace heredoc-in-command-substitution pattern with script-based release notes
generation to fix YAML parser interpretation issues.

Root cause:
- GitHub Actions YAML parser interprets heredoc content inside $() as YAML structure
- Line 149 error: parser expected ':' after '### Initial Release'
- Pattern: NOTES=$(cat <<EOF...) causes content to be parsed as YAML

Solution:
- Created scripts/generate-initial-release-notes.js (mirrors generate-release-notes.js)
- Script outputs markdown that YAML parser doesn't interpret
- Keeps --- separators (safe in script output, not in heredocs)
- Consistent pattern across workflow (all release notes from scripts)

Benefits:
- Fixes CI failures since Oct 24 (commit 0e26ea6)
- YAML validates successfully with Python yaml.safe_load()
- Easier to test and maintain release note generation
- No need to change --- to ___ separators

Testing:
- Script generates correct markdown locally
- YAML syntax validated
- TypeScript builds and type checks pass

Fixes: Release workflow runs 18806809439, 18806655633, 18806137471, etc.
Related: PR #371 (different approach attempted)

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

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

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

scripts/generate-initial-release-notes.js

@@ -0,0 +1,45 @@
+#!/usr/bin/env node
+
+/**
+ * Generate release notes for the initial release
+ * Used by GitHub Actions when no previous tag exists
+ */
+
+const { execSync } = require('child_process');
+
+function generateInitialReleaseNotes(version) {
+  try {
+    // Get total commit count
+    const commitCount = execSync('git rev-list --count HEAD', { encoding: 'utf8' }).trim();
+
+    // Generate release notes
+    const releaseNotes = [
+      '### 🎉 Initial Release',
+      '',
+      `This is the initial release of n8n-mcp v${version}.`,
+      '',
+      '---',
+      '',
+      '**Release Statistics:**',
+      `- Commit count: ${commitCount}`,
+      '- First release setup'
+    ];
+
+    return releaseNotes.join('\n');
+
+  } catch (error) {
+    console.error(`Error generating initial release notes: ${error.message}`);
+    return `Failed to generate initial release notes: ${error.message}`;
+  }
+}
+
+// Parse command line arguments
+const version = process.argv[2];
+
+if (!version) {
+  console.error('Usage: generate-initial-release-notes.js <version>');
+  process.exit(1);
+}
+
+const releaseNotes = generateInitialReleaseNotes(version);
+console.log(releaseNotes);