Fix MCP tool availability and shell escaping in tag mode

Pass MCP config and allowed tools through claude_args to ensure tools like
mcp__github_comment__update_claude_comment are properly available to Claude CLI.

Key changes:
- Tag mode outputs claude_args with MCP config (as JSON string) and allowed tools
- Fixed shell escaping vulnerability when JSON contains single quotes
- Agent mode passes through user-provided claude_args unchanged
- Re-added mcp_config input for users to provide custom MCP servers
- Cleaned up misleading comments and unused file operations
- Clarified test workflow is for fork testing

Security fix: Properly escape single quotes in MCP config JSON to prevent
shell injection vulnerabilities.

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

.github/workflows/claude-test.yml

@@ -0,0 +1,38 @@
+# Test workflow for km-anthropic fork (v1-dev branch)
+# This tests the fork implementation, not the main repo
+name: Claude Code (Fork Test)
+
+on:
+  issue_comment:
+    types: [created]
+  pull_request_review_comment:
+    types: [created]
+  issues:
+    types: [opened, assigned]
+  pull_request_review:
+    types: [submitted]
+
+jobs:
+  claude:
+    if: |
+      (github.event_name == 'issue_comment' && contains(github.event.comment.body, '@claude')) ||
+      (github.event_name == 'pull_request_review_comment' && contains(github.event.comment.body, '@claude')) ||
+      (github.event_name == 'pull_request_review' && contains(github.event.review.body, '@claude')) ||
+      (github.event_name == 'issues' && (
+        contains(github.event.issue.body, '@claude') || 
+        contains(github.event.issue.title, '@claude')
+      ))
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+      issues: write
+      id-token: write  # Required for OIDC token exchange
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        
+      - name: Run Claude Code
+        uses: km-anthropic/claude-code-action@v1-dev
+        with:
+          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}