Extend parameter templating to rule files

[Copilot]

Parameter substitution via -p flag (e.g., ${jira_issue_key}) only worked in task files. Rule files printed parameters verbatim.

Changes

• main.go: Apply os.Expand to rule content in ruleFileWalker, matching existing task behavior in emitTaskFileContent
• main_test.go: Add test coverage for parameter expansion in rules (both successful substitution and missing parameter preservation)

Example

# rule.md
Issue: ${jira_issue_key}
Project: ${project_name}

$ coding-context-cli -p jira_issue_key=PROJ-123 -p project_name=MyApp my-task
# Output now includes:
# Issue: PROJ-123
# Project: MyApp

Missing parameters preserve placeholder syntax: ${undefined_param}.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Extend templating to rules</issue_title>
<issue_description>Currently, we only template variables with in the tasks. I'd like to template them in the rules files too.

E.g. ${jira_issue_key} could be used in any rule file.</issue_description>

Comments on the Issue (you are @copilot in this section)

@alexec @swedishborgie thoughts?

• Fixes Extend templating to rules #106

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[Copilot]

Pull Request Overview

This PR extends parameter substitution (via the -p flag) from task files to rule files. Previously, parameters like ${jira_issue_key} only worked in task files, with rule files printing them verbatim. Now, both rule and task files support parameter expansion with identical behavior.

Key Changes:

• Parameter expansion now applies to rule file content using os.Expand
• Missing parameters preserve the placeholder syntax ${param_name}
• Table-driven tests added for both successful substitution and missing parameter handling

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
main.go	Added parameter expansion to ruleFileWalker function using os.Expand, matching the existing implementation in emitTaskFileContent
main_test.go	Added comprehensive test coverage with two new test cases for parameter substitution in rules (successful substitution and missing parameter preservation)