fix(members): read the default-branch roster as an inherited root after the reports switch

[jimpablo]

Summary

A team whose roster was written to the default branch by a pre-#489 CLI loses every member from members list / projects members once it upgrades past the orphan-branch split: the commands read only the teamai-reports worktree, which has no members/ yet, and the pre-switch copy on main was deliberately ignored (#489). The roster, unlike stats/sessions/votes, is never regenerated automatically — those come back as members report usage, while the roster needs one init per member — so an upgrading team just loses its member list.

This PR keeps the default-branch clone as a read-only inherited member root, the same pattern learnings already use (#485, learnings-roots.ts):

• memberReadRoots() / readMemberConfig() in src/members.ts — primary root first (reports worktree, or the clone for HTTP), default-branch clone as the lowest-precedence inherited root.
• members list and projects members list the union of both roots; when the same file exists on both, the reports-branch copy wins.
• Nothing is copied or deleted, and read-only commands still never publish the reports branch (the fix(members): avoid publishing reports branch from read-only queries #558 guarantee is unchanged and still asserted).
• Member registration (init, self-mode bootstrap) merges against the inherited copy, so a re-init preserves the original registeredAt/displayName/projects and writes the merged file to the reports branch — the data converges onto the branch gradually, one member at a time, with no migration step.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature causing existing behavior to change)
• Documentation only
• Refactor / internal cleanup

Test Plan

• npx tsc --noEmit passes
• npx vitest run passes — 272 files, 3885 passed | 1 skipped
• Added/updated tests for the change
  • src/__tests__/members.test.ts — the two tests that pinned "ignore leftover clone members" now pin the union + branch-copy-wins behavior; new memberReadRoots / readMemberConfig describes.
  • src/__tests__/git-kind-reports.test.ts — new real-git describe inherited member root (#735): pre-switch roster listed without copying/publishing, union + conflict through a real worktree. The existing "not copied or deleted" test is kept (renamed; its assertions are unchanged and still hold).
  • src/__tests__/projects-members.test.ts (new) — projects members inherited-root fallback.
  • src/__tests__/e2e/members-legacy-roster.test.ts (new) — built-CLI repro of [bug] 0.25.0版本 teamai members list报No team members registered #735 with a bare origin + isolated HOME.
• npm run build + full e2e: npx vitest run --config vitest.e2e.config.ts — 41 files passed | 3 skipped (live-provider files need credentials), 177 passed | 26 skipped, exit 0.

Real-CLI end-to-end records (built dist/index.js, macOS 15, Node v24.19.0, sandbox with a local bare origin):

1. The #735 repro — roster on main, no teamai-reports branch anywhere:

$ teamai members list

Team members (2):

  carol — Carol Pre
  dan
exit=0

$ git --git-dir=origin.git for-each-ref --format='%(refname:short)' refs/heads   # read stays read-only
main
$ ls ~/.teamai/reports-wt/members/    # nothing copied into the worktree
(empty or absent)

2. A teammate registers on the new CLI (origin grows teamai-reports with bob + a newer carol copy) — union, branch copy wins:

$ teamai members list

Team members (3):

  bob
  carol — Carol Branch
  dan
exit=0

3. Writer absorption — fresh machine, roster only on main, real teamai init (generic git provider):

$ teamai init https://fakehost.invalid/team/repo.git --scope user --agent claude --project billing --force
✔ Registered as team member: carol
✔ Member registered on the teamai-reports branch
✔ teamai initialized successfully!

$ git --git-dir=origin.git show teamai-reports:members/carol.yaml   # legacy fields absorbed
username: carol
displayName: Carol Pre        # from the pre-switch copy on main
registeredAt: 2025-01-01T00:00:00.000Z   # from the pre-switch copy on main
projects:
  - checkout                  # legacy project kept
  - billing                   # new project merged in

Related Issues

Fixes #735

Notes for Reviewers

• feat(git): route independent-clone reports onto teamai-reports #489 documented "leftover report files on main are ignored" as intentional, so this is a deliberate design change for members/ only — argued in the Summary: the roster cannot self-heal the way stats/sessions/votes do, and the inherited-root pattern is the one the repo already established for learnings in Write learnings/ to a teamai-learnings branch (direct push, no PR) #485. The usage guide now documents the asymmetry the other way: members/ keeps being read, other reports stay ignored.
• If you'd rather see a one-time migration that seeds the reports branch from the clone, the read path here would still be needed for machines that never re-init; happy to rework if you prefer that shape.
• isNewMember (the "Register member" vs "Update member roster" message) still keys off the worktree path only — a re-registering pre-switch member reports as newly registered on the branch, which seemed fine to keep surgical; say if you want that to consider the inherited root too.

[github-actions]

Findings

• [P1 blocking] src/init.ts:993 treats an inherited member as unchanged when the reports-branch file is absent. Consequently, initSelfRepo returns without writing the inherited entry; the same bug occurs at src/init.ts:1463 in normal init. Re-init only absorbs legacy data when a role/project changes, contradicting the documented gradual migration and leaving unchanged legacy members permanently on the default branch.
• [P1 blocking] src/members.ts:99 refreshes only teamai-reports for Git-backed repositories, then reads the inherited roster from the potentially stale default-branch checkout. projects members has the same problem at src/projects-cmd.ts:140. A machine whose clone predates later legacy registrations continues omitting those members even though they exist on origin/main; the default-branch root must be refreshed before forming the union.

The PR description includes both a test plan and real-CLI end-to-end records, so it satisfies the testing-documentation requirement.