Fix component release CI/CD workflows

[konard]

Summary

Fixes the CI/CD release path for the C# and Rust components after issue #75 showed that C# release failed and Rust auto-release skipped after successful validation jobs.

Root Cause

• C# release called scripts/merge-changesets.mjs --dir csharp/.changeset, but the script ignored --dir, still scanned root .changeset, and still used the template package placeholder MyPackage.
• Rust auto-release inherited skipped dependency behavior from the changelog/check dependency chain because the release job did not use the explicit always() && !cancelled() gating used by the Rust template.
• Shared release helpers ignored component metadata such as --tag-prefix and component changelog paths, so component releases could not reliably create csharp-v<version> or rust-v<version> releases.
• C# release packaging reused a pre-version artifact instead of packing after the version bump.

Changes

• Updated release helper scripts to honor component directories, package names, changelog paths, tag prefixes, and dry-run release payload generation.
• Added scripts/release-scripts.test.mjs to reproduce the failed helper behavior and guard the fixed paths.
• Updated C# CI/CD to run release-helper tests, pack NuGet after versioning, publish the post-version package, and create component-tagged GitHub releases from csharp/CHANGELOG.md.
• Updated Rust CI/CD to use explicit downstream/release gating, run release-helper tests, and create component-tagged GitHub releases from rust/CHANGELOG.md.
• Removed the duplicate generic .github/workflows/ci.yml; C# is consolidated in csharp.yml. wasm.yml remains separate because it owns WebAssembly and GitHub Pages deployment.
• Added the issue case study and downloaded evidence under docs/case-studies/issue-75/.

Verification

• node --test scripts/*.test.mjs
• npm run test:js
• ruby -e "require 'yaml'; Dir['.github/workflows/*.{yml,yaml}'].sort.each { |f| YAML.load_file(f); puts f }"
• dotnet test --configuration Release from csharp/
• dotnet pack --no-build --configuration Release --output /tmp/csharp-pack-test from csharp/
• cargo fmt --all -- --check from rust/
• cargo clippy --all-targets --all-features from rust/
• cargo test --all-features --verbose from rust/
• cargo test --doc --verbose from rust/
• node scripts/check-file-size.mjs --lang rust
• git diff --cached --check

Full downloaded run logs and local verification logs are included in docs/case-studies/issue-75/evidence/.

Fixes #75

[konard]

Working session summary

Implemented and pushed the fix to PR 76: #76

Commit: 36cc8908c95a8551fdb05995b13423c80833d2a3

What changed:

• Fixed C# and Rust release scripts to honor component paths, package names, tag prefixes, changelog paths, and dry-run behavior.
• Updated C# and Rust workflows so downstream release/build jobs handle skipped dependencies correctly.
• Removed the duplicate generic CI workflow.
• Added script-level regression tests and a case study with preserved CI evidence under docs/case-studies/issue-75.

Verification:

• Fresh PR checks are passing; release-only jobs are skipped as expected for this PR context.
• Local checks passed for JS script tests, workflow YAML parsing, C# tests/pack, Rust fmt/clippy/tests/doc tests, and Rust file-size checks.
• Working tree is clean.
• PR title/body were updated and the PR is ready for review.

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This summary was automatically extracted from the AI working session output.

[konard]

🤖 Solution Draft Log

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[konard]

🎉 Auto-merged

This pull request has been automatically merged by hive-mind.

• All CI checks have passed

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Auto-merged by hive-mind with --auto-merge flag