feat: add Toolnames checkup workflow to prevent duplicate tool-name issues

[Copilot]

Summary

Closes the gap identified in #378 — where a tool-name issue was submitted but the tool was already mapped in src/toolNames.json on main.

Changes

New workflow: .github/workflows/check-toolnames.yml

check-toolnames (triggered when the "Toolnames checkup" label is added to any issue)

• Checks out main and reads src/toolNames.json.
• Extracts backtick-wrapped identifiers from the issue body (filtering out file paths and strings with spaces to reduce false positives).
• Posts a comment on the issue with a table showing:
  • ✅ Already mapped — tools that are already in toolNames.json (issue is a duplicate)
  • ❌ Not yet added — tools that genuinely need to be mapped

Extension update: src/webview/usage/main.ts

createMcpToolIssueUrl() now applies both the "MCP Toolnames" and "Toolnames checkup" labels when a user opens an issue from the extension's "Report unknown tools" button. This means the checkup workflow fires automatically on every new issue — no maintainer action required.

How to use

1. Merge this PR.
2. Issues opened from the extension automatically carry both labels, triggering the checkup workflow immediately.
3. The workflow posts a comment showing which tool names are already mapped and which still need to be added.

Workflow run link

${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}

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[rajbos]

@copilot , also update the extension code to include this label when the user creates the issue with the missing toolnames from the extension.

[Copilot]

@copilot , also update the extension code to include this label when the user creates the issue with the missing toolnames from the extension.

Done in commit aae7f62. createMcpToolIssueUrl in src/webview/usage/main.ts now includes both labels:

const labels = encodeURIComponent('MCP Toolnames,Toolnames checkup');

Issues created from the extension will automatically carry both labels, so the checkup workflow fires immediately without a maintainer having to add the label manually. Also removed the now-unnecessary setup-label job and workflow_dispatch trigger from the workflow.

[rajbos]

Reverted the adding of both labels automatically to potentially prevent issues auto running workflows with issues:write access.