docs: add new-package checklist to CLAUDE.md

CLAUDE.md

@@ -0,0 +1,51 @@
+# CLAUDE.md
+
+## Adding a new package to the monorepo
+
+When scaffolding a new `packages/forest_admin_datasource_*` (or any new)
+package, mirror an existing package's scaffold (`Gemfile`, `Gemfile-test`,
+`Rakefile`, `.rspec`, gemspec, `LICENSE`, `spec/spec_helper.rb`, `.gitignore`)
+and update every one of these in the same PR — missing one breaks CI or
+releases silently, not loudly:
+
+1. **`lib/<package>/version.rb`** — must be exactly:
+   ```ruby
+   module <Module>
+     VERSION = "0.1.0"
+   end
+   ```
+   Double quotes, no `.freeze`. The release sed in `.releaserc.js` only
+   matches this exact format.
+
+2. **New `.gemspec`** — explicitly opt out of RubyGems MFA, matching every
+   other package:
+   ```ruby
+   spec.metadata['rubygems_mfa_required'] = 'false'
+   ```
+   Gem publishing runs unattended from CI (`.releaserc.js`), so it can't
+   satisfy an MFA prompt.
+
+3. **`.rubocop.yml`** — add the new `version.rb` to:
+   - `Style/MutableConstant` Exclude
+   - `Style/StringLiterals` Exclude
+
+   And the new `.gemspec` to `Gemspec/RequireMFA` Exclude — the cop flags
+   the `'false'` opt-out from step 2 as an offense, so it needs suppressing.
+
+   (Other per-file excludes — `Metrics/MethodLength`, `Metrics/BlockLength`,
+   `Naming/PredicatePrefix` — are added case-by-case only if the cop actually
+   fires; don't copy them blindly.)
+
+4. **`.releaserc.js`** — add the package in all three spots:
+   - `prepareCmd`: `sed -i 's/VERSION = ".*"/VERSION = "${nextRelease.version}"/g' packages/<package>/lib/<package>/version.rb;`
+   - `successCmd`: `( cd packages/<package> && gem build && gem push <package>-*.gem );`
+   - `@semantic-release/git` `assets`: `packages/<package>/lib/<package>/version.rb`
+
+5. **`.github/workflows/build.yml`** — add the package name to:
+   - the `lint` job's `packages` matrix
+   - the `test` job's `packages` matrix
+   - the codecov step's `files:` list (`.../<package>/coverage.json`)
+
+After merging, verify the next release actually bumps the new `version.rb` —
+the sed in step 4 silently no-ops if the format from step 1 is off, with no
+CI failure to catch it.