Add compiler validation to detect @include/@import directives inside template regions

[Copilot]

Problem

The compiler was not validating that @include and @import directives are used correctly with template conditional blocks. This created ambiguity because:

• Template conditionals ({{#if...}}{{/if}}) are processed at runtime by GitHub Actions
• Include directives are processed at compile time by the compiler
• Having includes inside conditionals would create confusion about when to expand them

Solution

Added a new validation function validateNoIncludesInTemplateRegions() that:

1. Scans markdown content for all {{#if...}}{{/if}} template regions
2. Checks each line within template blocks for @include or @import directives
3. Handles indented includes by trimming whitespace before pattern matching
4. Returns a clear error message indicating the problematic directive and its location

The validation is integrated into ParseWorkflowFile() before include expansion, ensuring we catch issues early with the raw markdown content.

Example

Before - This would compile without error (causing confusion):

{{#if github.event.issue.number}}
@include shared/tools.md
This creates ambiguity!
{{/if}}

After - Now raises a clear error:

✗ failed to parse workflow file: template region validation failed: 
@include/@import directives cannot be used inside template regions 
({{#if...}}{{/if}}): found '@include shared/tools.md' at line 2 within template block

Correct usage - Includes outside templates work as expected:

@include shared/tools.md

{{#if github.event.issue.number}}
Content here is fine!
{{/if}}

Testing

• Added 18 unit tests covering various scenarios (nested templates, indented includes, optional includes, section references)
• Added 4 integration tests with the compiler
• All existing tests continue to pass
• make agent-finish validates all checks pass

Fixes the issue where includes inside template regions could cause compilation or runtime confusion.

Original prompt

Add a compiler checks that detects usage of @include/import commands inside template regions ({{#if...). Raise an error.

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