Add copilot-instructions.md

[stas-sbi]

No description provided.

[Copilot]

Pull Request Overview

Adds a new documentation file outlining guidelines for GitHub workflows and shell scripts.

• Specifies workflow permission settings and version pinning rules
• Enforces use of environment variables in shell snippets
• Requires shell scripts to pass ShellCheck

Comments suppressed due to low confidence (4)

.github/copilot-instructions.md:4

• Clarify that in YAML this should appear as permissions: {} rather than a string literal '{}' to avoid confusion.

- permissions are set to '{}' for workflow and overridden for each job where needed

.github/copilot-instructions.md:5

• [nitpick] Use consistent casing for GitHub and consider rephrasing to "official GitHub Actions" for clarity.

- versions of github actions are pinned to a specific commit unless the action belongs to one of: the same organization (global-synchronizer-foundation), github official actions

.github/copilot-instructions.md:6

• [nitpick] Consider rewording to explicitly state: "In run: steps, avoid template placeholders; use environment variables instead."

- shell snippets (under `run:`) don't have templated variables and environment variables are used instead

.github/copilot-instructions.md:9

• [nitpick] Expand this to "Shell scripts must pass ShellCheck linting without warnings" for clearer requirements.

- conforms to ShellCheck

[stas-sbi]

@tkatrichenko would you help me to review this and then we'd run these instructions against another PR?

[tkatrichenko]

Yeah. Let's try it with my PR