Fix template conditional expressions creating invalid YAML in heredocs

[Copilot]

Template conditionals like {{#if github.event.issue.number}} were being wrapped with ${{ }} after expression extraction, creating invalid YAML syntax in heredocs:

{{#if ${{ github.event.issue.number }} }}  # ❌ Invalid - GitHub Actions tries to evaluate this

Root cause: Expression wrapping happened after extraction, so newly created ${{ }} expressions were never replaced with placeholders.

Fix: Reorder compilation to wrap conditionals before extracting expressions:

// Before (wrong order)
extractExpressions()      // Extracts ${{ github.event.issue.number }}
replaceWithPlaceholders() // Replaces with __GH_AW_*__
wrapConditionals()        // Creates NEW ${{ }} that never get extracted ❌

// After (correct order)  
wrapConditionals()        // Creates {{#if ${{ github.event.issue.number }} }}
extractExpressions()      // Extracts ALL ${{ }} including wrapped ones
replaceWithPlaceholders() // Replaces ALL with __GH_AW_*__ ✅

Result:

{{#if __GH_AW_GITHUB_EVENT_ISSUE_NUMBER__ }}  # ✅ Valid - placeholder replaced at runtime

Changes:

• Moved wrapExpressionsInTemplateConditionals() before expression extraction in compiler_yaml.go
• Updated tests to validate placeholder replacement instead of direct expression wrapping

Original prompt

The conditional template experssion in {{#if ... }} should expanded to github action expression and then replaced by environment variables before being written to heredoc.

You can see this with

https://github.com/githubnext/gh-aw/blob/main/.github/workflows/cloclo.md?plain=1#L66C1-L66C34

The rendered lock file results in an invalid expression that breaks the yaml file.

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