docs: add GitHub issue templates and pull request template

[Amnoor]

Summary

This PR adds a full suite of GitHub issue templates and a pull request template to .github/. Six structured YAML issue templates cover every contribution type the project accepts. A config.yml disables blank issues and surfaces the private security reporting link. A PULL_REQUEST_TEMPLATE.md pre-fills the three-section PR description structure defined in CONTRIBUTING.md.

Files Changed

Added:

• .github/
  • PULL_REQUEST_TEMPLATE.md
  • ISSUE_TEMPLATE/
    • bug-report.yml
    • config.yml
    • documentation-issue.yml
    • feature-request.yml
    • new-platform-request.yml
    • node-version-bump.yml
    • tzdata-version-bump.yml

Modified:

• None

Deleted:

• None

Key Changes

• Added bug-report.yml — structured form for image misbehaviour reports. Requires the affected version tag, registry (Docker Hub or GHCR), platform (linux/amd64 or linux/arm64), description, steps to reproduce, actual behaviour, and expected behaviour. Includes a pre-flight note directing security vulnerabilities to SECURITY.md rather than this form.
• Added config.yml — disables blank issue creation (blank_issues_enabled: false) and adds a Report a Security Vulnerability contact link pointing directly to GitHub Private Vulnerability Reporting (/security/advisories/new), preventing security issues from being filed as public issues.
• Added documentation-issue.yml — structured form for documentation errors across README.md, CONTRIBUTING.md, SECURITY.md, CODE_OF_CONDUCT.md, or other files. Requires the affected file, issue type (typo, outdated version reference, incorrect content, broken link, incorrect code example, missing information, or other), the exact location, and the correct content.
• Added feature-request.yml — structured form for proposing new image capabilities. Requires a description, a justification explaining strict runtime necessity, and a distroless impact assessment confirming the addition does not introduce a shell, package manager, or OS utility. Optional fields for proposed implementation and additional context.
• Added new-platform-request.yml — structured form specifically for new build target platform or architecture requests (e.g. linux/arm/v7), distinct from a general feature request. Requires the exact Docker platform string, confirmation of an official Alpine Node.js image for that platform, confirmation of QEMU support in GitHub Actions, and a use case description.
• Added node-version-bump.yml — structured form for requesting a Node.js version upgrade. Requires the current and requested version and the exact Alpine image tag. Includes a note that version bumps always result in at minimum a major semver release.
• Added tzdata-version-bump.yml — structured form for requesting a tzdata Alpine package upgrade. Requires the current pinned version, the requested version, and confirmation of availability in the Alpine 3.22 package repository.
• Added PULL_REQUEST_TEMPLATE.md — pre-fills the three required PR description sections (Summary, Files Changed, Key Changes) with inline HTML comments as author guidance, matching the structure defined in CONTRIBUTING.md.