Add GitHub Copilot agent setup workflow

[Copilot]

This PR implements a GitHub workflow to help the Copilot coding agent understand how to set up the development environment for the FerretDB/wire project.

Changes Made

• Added .github/workflows/copilot-setup-steps.yml with a single copilot-setup-steps job
• Included all essential development environment setup steps:
  • Go environment setup using the project's custom GitHub action
  • Development tools installation (Task, linters, code generators)
  • Project dependency initialization
  • Code generation and formatting
  • Basic setup verification

Implementation Details

The workflow follows the exact same patterns as the existing go.yml workflow to ensure consistency:

• Uses FerretDB/github-actions/setup-go@main (same as existing workflows)
• Uses the same Task-based build system commands
• Includes the same tool installation and initialization steps
• Provides clear, descriptive step names for better Copilot understanding

This allows the GitHub Copilot coding agent to understand the development setup process for this Go-based MongoDB wire protocol implementation project, including its specific toolchain requirements and build system.

Fixes #149.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.06%. Comparing base (712828f) to head (39107dd).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #150   +/-   ##
=======================================
  Coverage   60.06%   60.06%           
=======================================
  Files          44       44           
  Lines        2935     2935           
=======================================
  Hits         1763     1763           
  Misses        927      927           
  Partials      245      245           

Flag	Coverage Δ
test	60.06% <ø> (ø)

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To address the issue, add an explicit permissions block to the workflow. Since the workflow involves checking out code and running local tasks, it only needs read access to the repository contents and does not require write permissions. The permissions block should be added at the workflow level (root) to apply the least privilege configuration to all jobs within the workflow.

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