Improve copilot instructions accuracy and completeness

[GernotMaier]

Fixes several inaccuracies and gaps in the Copilot instructions file:

• Add missing reporting/ and schemas/ entries to the project structure
• Add missing components/ and data-model/ subdirs to docs source structure
• Fix isort reference: imports are sorted via ruff's I ruleset, not a standalone isort tool
• Fix changelog fragment naming: use <pr-number> (not <issue>) and clarify wording
• Simplify default pytest command to bare pytest (testpaths already set in pyproject.toml)

[ctao-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[Copilot]

Pull request overview

Updates the repository’s Copilot instructions and related housekeeping files to better reflect the actual project structure and development workflow, and adds a changelog fragment documenting the maintenance change.

Changes:

• Extend the documented project/docs directory tree to include missing subdirectories.
• Update testing and linting guidance to match current pyproject.toml configuration (pytest testpaths, ruff import sorting).
• Add .gitignore entries for grid output and VS Code workspace/settings, plus a maintenance changelog fragment.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/changes/2136.maintenance.md	Adds a Towncrier fragment describing the instructions update.
.gitignore	Ignores additional generated output and VS Code local configuration files.
.github/copilot-instructions.md	Corrects/extends documentation for repo structure, testing defaults, and lint/import sorting; adds PR/changelog guidance.