chore: add update-packages Copilot CLI skill (#103)

* chore: add update-packages skill for Copilot CLI

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: move update-packages skill to .claude/skills

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: remove repo-specific workflow from update-packages skill

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: remove Copilot co-author trailer from skill example

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: generalize major version omit guidance in update-packages skill

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: chrisjwalk-bot

.claude/skills/update-packages/SKILL.md

@@ -0,0 +1,102 @@
+---
+name: update-packages
+description: >
+  Update all npm packages to their latest versions using the update-packages
+  script. Use this when asked to update, upgrade, or consolidate dependencies,
+  or to close dependabot PRs.
+---
+
+## Update Packages Workflow
+
+Follow these steps in order.
+
+### 1. Create a GitHub issue to track the update
+
+```bash
+gh issue create --title "chore: update all packages to latest" --body "..."
+```
+
+Note the issue number (e.g. #42).
+
+### 2. Create a branch off main
+
+```bash
+git checkout main && git pull
+git checkout -b feat/consolidate-deps-<issue-number>
+```
+
+### 3. Run the update-packages script
+
+Use `--omit` to skip any packages with known breaking changes or major version
+bumps that need separate handling. Major version upgrades should be omitted by
+default unless you've verified they are safe.
+
+```bash
+npx ts-node ./tools/update-packages/src/main.ts --omit typescript --interactive false
+```
+
+The script will:
+
+- Detect all outdated packages via `pnpm outdated`
+- Run `nx migrate <pkg>@latest` for each one
+- Merge any generated migrations into `migrations.json`
+- Print next steps (install + run migrations if needed)
+
+### 4. Install updated packages
+
+```bash
+pnpm install --no-frozen-lockfile
+```
+
+If the install fails, check for postinstall build errors (e.g. tsconfig
+issues in `tools/builders/dotnet-builder`).
+
+### 5. Run migrations (only if migrations.json was updated)
+
+```bash
+npx nx migrate --run-migrations
+```
+
+### 6. Run all tests
+
+```bash
+nx reset
+nx run-many -t build,test
+```
+
+All 9 projects must pass before committing.
+
+### 7. Commit
+
+```bash
+git add -A
+git commit -m "chore: update all packages to latest (closes #<issue-number>)"
+```
+
+### 8. Push and open PR
+
+```bash
+git push origin feat/consolidate-deps-<issue-number>
+gh pr create --title "chore: update all packages to latest" --body "Closes #<issue-number> ..."
+```
+
+### 9. Close stale dependabot PRs
+
+Close any open dependabot PRs that are now covered by this update:
+
+```bash
+gh pr list --author "app/dependabot" --json number,title
+gh pr close <number> --comment "Covered by consolidated update PR" --delete-branch
+```
+
+Leave open any dependabot PRs for packages that were intentionally omitted
+(e.g. TypeScript major version bumps).
+
+## Notes
+
+- Omit packages with major version bumps by default — run them separately once
+  you've confirmed they are safe (e.g. no breaking changes affecting the codebase)
+- If a package is a transitive dep not shown by `pnpm outdated`, use
+  `pnpm.overrides` in `package.json` to force the version
+- After merging, watch for new dependabot PRs — dependabot may recreate stale
+  ones; close them if the package was already updated