feat(actions): add common issue lifecycle workflows

[uwe-mayer]

Summary

Introduces shared issue lifecycle workflows and documentation for use across all cloudoperators repositories.

New files:

• ISSUE_LIFECYCLE.md — Single source of truth for the issue triage/refinement/backlog workflow
• skills/issue-triage.md — AI agent skill for automated issue triage
• workflows/issue-triage/action.yaml — Composite action: auto-labels needs-triage + posts welcome comment on new issues
• workflows/issue-project-sync/action.yaml — Composite action: adds issues to project feat:(actions) share actions #9 when backlog label is applied

Updated:

• CONTRIBUTING.md — Now references the shared ISSUE_LIFECYCLE.md

Setup required after merge:

1. Create org-level secret GH_PROJECT_TOKEN (PAT with project + repo scopes) shared with: greenhouse, shoot-grafter, repo-guard, cloudctl, owner-label-injector
2. Merge dependent PRs in consuming repos (they reference cloudoperators/common/workflows/...@main)

[Copilot]

Pull request overview

Adds a shared, organization-wide issue lifecycle process and two reusable composite actions to automate early issue hygiene (triage labeling + project intake) across cloudoperators repositories.

Changes:

• Introduces issue-triage composite action + documentation to auto-label newly opened issues and post a welcome comment.
• Introduces issue-project-sync composite action + documentation to add issues to org project #9 when the backlog label is applied.
• Adds org-wide Issue Lifecycle + agent skill documentation and updates contributing guidelines to reference it.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
workflows/issue-triage/README.md	Documents how to consume the issue triage composite action across repos.
workflows/issue-triage/action.yaml	Implements labeling + welcome-comment automation for newly opened issues.
workflows/issue-project-sync/README.md	Documents how to consume the project-sync composite action and required secret/labels.
workflows/issue-project-sync/action.yaml	Implements GraphQL-based addition of labeled issues to org project #9.
skills/issue-triage.md	Defines an agent “skill” playbook for consistent triage decisions/labels.
ISSUE_LIFECYCLE.md	Defines the canonical issue workflow, labels, and lifecycle stages.
CONTRIBUTING.md	Updates contributing guidance to point to the shared issue lifecycle doc.

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[abhijith-darshan]

Suggested change

	with:
	project-url: ${{ inputs.PROJECT_URL }}
	github-token: ${{ inputs.GH_TOKEN }}
	with:
	project-url: ${{ inputs.PROJECT_URL }}
	github-token: ${{ inputs.GH_TOKEN }}
	labeled: needs-refinement