Add release procedure and automation gates

[simsong-codex]

Summary

• replace the release checklist with a complete release procedure and release-issue template
• make make release a thin, fail-closed entry point to an isolated-worktree release script
• retain Makefile leaf targets for distcheck and container validation
• add containerized Ubuntu/Fedora distcheck gates and Finch/Colima guidance
• add draft-PR job gating so planning and release-preparation PRs do not consume repository-managed Actions runners until marked ready

Validation

• YAML parsing and git diff --check passed
• bash -n scripts/release.sh passed
• verified Makefile container-target expansion and source-distribution manifest inclusion
• verified make release fails before creating a worktree when required artifacts are absent
• native Finch Ubuntu attempt reached the container build but Docker Hub metadata retrieval timed out before distcheck could run

CI behavior

This is deliberately a draft PR. Repository-managed CI jobs should appear skipped while it remains a draft, then run on ready_for_review. GitHub default CodeQL is separately configured; its one draft run was cancelled.

[Copilot]

Pull request overview

This PR formalizes the project’s release process by replacing the old checklist with a detailed release procedure and a release-issue template, and adds tooling/CI gates to make release preparation more reproducible and less likely to consume CI resources prematurely.

Changes:

• Add make release orchestration that runs an isolated-worktree release assembly script (scripts/release.sh) and stages artifacts + checksums.
• Add containerized Ubuntu/Fedora distcheck gates (Dockerfiles + Makefile targets) and update .dockerignore for container contexts.
• Update multiple GitHub Actions workflows to skip runner-consuming jobs while PRs are drafts (run on ready_for_review).

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
scripts/release.sh	New isolated-worktree release assembly script that runs distcheck gates and stages artifacts/logs/checksums.
Makefile.am	Adds release target plus container distcheck targets; ensures release assets are distributed.
etc/Dockerfile.ubuntu-distcheck	Ubuntu container build that installs deps (incl. libewf legacy) and runs make distcheck.
etc/Dockerfile.fedora-distcheck	Fedora container build that installs deps (incl. libewf legacy) and runs make distcheck.
doc/RELEASE_PROCEDURE.md	New end-to-end release procedure documenting gates, artifact assembly, and publication workflow.
doc/RELEASE_CHECKLIST.txt	Removes the old manual checklist in favor of the new procedure.
AGENTS.md	Expands AI contributor instructions (commit identity/signing verification and branch cleanup guidance).
.github/workflows/mingw.yml	Skips MinGW job for draft PRs; runs when marked ready for review.
.github/workflows/latex-docs.yml	Skips LaTeX docs job for draft PRs; runs when marked ready for review.
.github/workflows/codecov.yml	Skips Codecov job for draft PRs; runs when marked ready for review.
.github/workflows/ci-cd.yml	Skips CI jobs for draft PRs; runs when marked ready for review.
.github/ISSUE_TEMPLATE/release.yml	Adds a structured release issue template to record evidence and artifact provenance safely.
.dockerignore	Expands ignores to keep Docker build contexts clean and avoid including release staging dirs/artifacts.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.49%. Comparing base (0b21e6e) to head (bc2b992).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #625   +/-   ##
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  Coverage   77.49%   77.49%           
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  Files         118      118           
  Lines       14119    14119           
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  Hits        10941    10941           
  Misses       3178     3178           

Flag	Coverage Δ
unittests	77.49% <ø> (ø)

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