fix(github): pass repositoryPath to GitHubIndexer in agent initialization

Fixes CI test failures where getCurrentRepository() was being called
without a repository parameter, causing tests to fail in CI environment
where .git folder or gh CLI may not be configured.

**Root Cause:**
GitHubAgent.initialize() was creating GitHubIndexer with only codeIndexer,
missing the repositoryPath parameter. This caused the indexer to fall back
to getCurrentRepository(), which fails in CI.

**Fix:**
Pass this.config.repositoryPath as second argument to GitHubIndexer constructor.

**Testing:**
- All 14 integration tests pass locally ✅
- Should fix CI failures in PR #24

Author: prosdev

packages/subagents/src/github/agent.ts

@@ -35,7 +35,7 @@ export class GitHubAgent implements Agent {
     this.context = context;
     this.name = context.agentName;
 
-    this.indexer = new GitHubIndexer(this.config.codeIndexer);
+    this.indexer = new GitHubIndexer(this.config.codeIndexer, this.config.repositoryPath);
 
     context.logger.info('GitHub agent initialized', {
       capabilities: this.capabilities,