chore: Overhaul release workflow using home-cooked solution

[maximilianruesch]

Uses a homecooked release PR solution that suits our needs.

Disclosure: The base of this PR was generated by Copilot, but was later refactored. The initial pitch included tooling tests, but I have removed those (in an extra commit). We could restore them, but they need some updating in that case.

Closes #1866
Closes #1867

[github-actions]

Bencher Report

Branch	mr/chore/new-release-workflow
Testbed	Linux

Click to view all benchmark results

Benchmark	hugr_bytes	Benchmark Result bytes x 1e3 (Result Δ%)	Upper Boundary bytes x 1e3 (Limit %)	hugr_nodes	Benchmark Result nodes (Result Δ%)	Upper Boundary nodes (Limit %)
tests/benchmarks/test_big_array.py::test_big_array_compile	📈 view plot 🚷 view threshold	154.02 x 1e3 (0.00%) Baseline: 154.02 x 1e3	155.56 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	6,630.00 (0.00%) Baseline: 6,630.00	6,696.30 (99.01%)
tests/benchmarks/test_ctrl_flow.py::test_many_ctrl_flow_compile	📈 view plot 🚷 view threshold	27.71 x 1e3 (0.00%) Baseline: 27.71 x 1e3	27.99 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	1,051.00 (0.00%) Baseline: 1,051.00	1,061.51 (99.01%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_benchmark_compile	📈 view plot 🚷 view threshold	10.09 x 1e3 (+0.01%) Baseline: 10.09 x 1e3	10.19 x 1e3 (99.02%)	📈 view plot 🚷 view threshold	301.00 (0.00%) Baseline: 301.00	304.01 (99.01%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_pop_benchmark_compile	📈 view plot 🚷 view threshold	13.70 x 1e3 (0.00%) Baseline: 13.70 x 1e3	13.83 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	420.00 (0.00%) Baseline: 420.00	424.20 (99.01%)

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.85%. Comparing base (3c19192) to head (7579b2c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1887   +/-   ##
=======================================
  Coverage   92.85%   92.85%           
=======================================
  Files         148      148           
  Lines       13849    13849           
=======================================
  Hits        12859    12859           
  Misses        990      990           

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[codspeed-hq]

Merging this PR will not alter performance

✅ 11 untouched benchmarks

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_{Comparing mr/chore/new-release-workflow (7579b2c) with main (0ca86f7)}

[ss2165]

Please include some test CI runs of the relevant workflows

[maximilianruesch]

@ss2165 Most of the PR based workflows have been tested in #1889, I am careful with testing tag + release based stuff in the repository itself; it is too easy to fetch (and subsequently repush) unwanted tags.

[Copilot]

Pull request overview

This PR replaces the existing release-please based automation with a custom, tag-driven release workflow for the guppylang monorepo, including new scripts to compute versions, seed/update changelogs, and keep a release-notes preview in sync on the release PR.

Changes:

• Introduces custom release automation workflows (release-pr, changelog preview sync, major-bump guard, and tag-driven release creation).
• Adds release helper scripts for version computation, changelog extraction/insertion, and PR body rendering; adds a git-cliff config for draft changelog seeding.
• Removes release-please configuration/manifest and updates docs and CI gating to match the new release-PR branch naming.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
scripts/release/update_changelog.py	New helper to splice a generated version section into CHANGELOG.md.
scripts/release/render_pr_body.py	New helper to render/replace the release-notes preview block in a release PR body.
scripts/release/extract_changelog.py	New helper to extract a version’s changelog body for release notes.
scripts/release/compute_versions.py	New version bump logic for guppylang and the new internals <major>.<build> scheme.
cliff.toml	New git-cliff configuration used to seed draft changelog sections per package.
ruff.toml	Adds a per-file ignore for scripts/release/* CLI printing.
.github/workflows/release-pr.yml	New workflow to open/update a single release PR and bump versions/lock/changelogs.
.github/workflows/release-pr-changelog-preview.yml	New workflow to keep the PR body preview in sync with committed changelogs.
.github/workflows/release-major-guard.yml	New workflow to block accidental major bumps unless explicitly labeled.
.github/workflows/release-publish.yml	New tag-driven workflow to create draft GitHub releases and populate notes from changelogs.
.github/actions/update-release-preview/action.yml	New composite action used to update the PR body preview via GH CLI.
.github/workflows/release-checks.yml	Adapts release checks to run on the new release-pr--* branches and updates version verification source.
.github/workflows/python-wheels.yml	Updates gating logic to recognize the new release PR branch naming.
guppylang/src/guppylang/init.py	Updates comment to reflect the new release workflow as the version sync mechanism.
guppylang-internals/src/guppylang_internals/init.py	Updates comment to reflect the new release workflow as the version sync mechanism.
guppylang-internals/src/guppylang_internals/engine.py	Parses internals versions that may omit minor/patch per new scheme.
DEVELOPMENT.md	Updates release process documentation to match the new custom workflows.
release-please-config.json	Removed (release-please no longer used).
.release-please-manifest.json	Removed (release-please no longer used).
.github/workflows/release-please.yml	Removed (release-please no longer used).

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Pull request overview

Copilot reviewed 20 out of 20 changed files in this pull request and generated 6 comments.