fix: migrate achievements to projectsV2 and guard null commit arrays (activity, habits)

[ShawnXxy]

Problem

Three plugins currently render a red "Unexpected error" box on generated metrics, even though the action run reports success. All three fail during rendering with the errors below (captured from a live run):

{ name: 'achievements', result: { error: {
  message: 'Unexpected error',
  instance: GraphqlResponseError: ... Projects (classic) is being deprecated ...
  response: { data: { user: null }, errors: [ { type: 'NOT_FOUND', path: ['user','projects'] } ] } } } }

{ name: 'activity', result: { error: {
  message: 'Unexpected error',
  instance: TypeError: Cannot read properties of undefined (reading 'filter')
    at source/plugins/activity/index.mjs:140 } } }

{ name: 'habits', result: { error: {
  message: 'Unexpected error',
  instance: TypeError: Cannot destructure property 'author' of 'undefined' as it is undefined.
    at source/plugins/habits/index.mjs:51 } } }

Root causes & fixes

1. achievements — Projects (classic) deprecation (fixes #1706)

The AchievementsDefault query requests user.projects (Projects classic), which GitHub has sunset. The GraphQL API now returns a NOT_FOUND response error for that field, which nulls the entire user object and makes the whole plugin throw.

Fix: query projectsV2 instead for the "Manager" achievement (achievements.graphql + list/users.mjs).

2 & 3. activity / habits — PushEvent with no commits

GitHub's Events API can return a PushEvent whose payload has no commits array. activity then calls .filter on undefined, and habits flat-maps undefined into the patch loader and destructures author from it — both throw.

Fix: default the missing array to [] in both plugins.

Changes

• source/plugins/achievements/queries/achievements.graphql — projects → projectsV2
• source/plugins/achievements/list/users.mjs — user.projects → user.projectsV2
• source/plugins/activity/index.mjs — commits = (commits ?? []).filter(...)
• source/plugins/habits/index.mjs — .flatMap(({payload}) => payload.commits ?? [])

Notes

• projectsV2 reads require the read:project / project token scope (already present for tokens that render this plugin).
• Verified on a live profile: the three "Unexpected error" boxes are gone and the sections render normally.