ci: prevent duplicate workflow runs for xgopilot branches

[luoliwoshang]

Summary

This PR fixes issue #1340 by preventing duplicate CI workflow runs for xgopilot branches.

Changes

Added !xgopilot/** exclusion pattern to all workflow files, matching the existing !dependabot/** pattern:

• ✅ .github/workflows/targets.yml
• ✅ .github/workflows/llgo.yml
• ✅ .github/workflows/go.yml
• ✅ .github/workflows/fmt.yml
• ✅ .github/workflows/doc.yml
• ✅ .github/workflows/release-build.yml

Impact

After this change:

• xgopilot branches will only trigger CI checks on pull_request events
• Push events to xgopilot branches will be ignored
• This eliminates redundant CI runs and reduces resource usage
• Matches the existing behavior for dependabot branches

Test Plan

• Verify that this PR itself only triggers CI on the pull_request event
• Confirm no push event workflows run for the fix-ci-duplicate-runs branch
• Check that all workflow syntax is valid

Fixes #1340

🤖 Generated with Claude Code

[gemini-code-assist]

Note

Gemini is unable to generate a summary for this pull request due to the file types involved not being currently supported.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.18%. Comparing base (1ee4da9) to head (bf05779).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1341   +/-   ##
=======================================
  Coverage   90.18%   90.18%           
=======================================
  Files          43       43           
  Lines       12674    12674           
=======================================
  Hits        11430    11430           
  Misses       1087     1087           
  Partials      157      157           

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[xgopilot]

✅ Code Review Complete

This PR is well-implemented with consistent changes across all workflow files. The !xgopilot/** exclusion pattern correctly prevents duplicate CI runs while maintaining full test coverage via pull request triggers. No noteworthy issues found in code quality, performance, documentation, or security aspects.