feat(server): Team registry: core workspace structure + team CRUD #630

[tarikcosovic97]

Linked issue

Closes #630

Summary of changes

Delivers the minimum team-registry write surface that unblocks the v4.1 human-in-the-loop chain (#632, #600, #609, #586, #587). Sole writer of a new tracked file .bot/team-registry.json; three CLI commands (team add / list / get); schema validation + actionable errors. Mothership sync (#601), lifecycle commands (remove/update/set-availability, role-* — #631), and hosting (#576) are all handled elsewhere.

Files touched:

src/runtime/Modules/Dotbot.TeamRegistry/ — new module. Sole writer of the registry file; read/add/get/assert helpers.
src/cli/team-{add,list,get}.ps1 — thin CLI wrappers over the module. Both positional and --flag argument forms supported.
bin/dotbot.ps1 — Invoke-Team dispatcher + team switch branch + help entries.
tests/Test-TeamRegistry.ps1 — Layer 2 test file registered in tests/Run-Tests.ps1.
README.md — three team commands added to the Commands table.
Registry shape (schema_version: 1):

{
  "schema_version": 1,
  "members": [
    { "id": "tm_a1b2c3d4",
      "name": "ana-smith",
      "email": "ana@example.com",
      "role": "developer",
      "created_at": "2026-07-17T13:00:00Z",
      "created_by": "cli" }
  ]
}

Reviewer feedback applied:

Path corrected to .bot/team-registry.json (directly under .bot/, git-tracked).
email is required — needed by downstream Q&A routing; basic user@domain.tld validation.
role constrained to developer | lead | reviewer | qa; invalid values rejected with a message that names the allowed set.
id generation contract documented: tm_ + 8 chars uniform-drawn from [0-9a-zA-Z] via CSRNG rejection sampling; belt-and-suspenders collision retry.
Add-DotbotTeamMember serializes read-modify-write under a named System.Threading.Mutex keyed on a hash of the registry path. Prevents lost updates from concurrent adds. Atomic temp-file rename on top guards readers from torn files.
Branch cut from releases/4.1.0, not main.
Testing notes
pwsh tests/Test-TeamRegistry.ps1 # focused
pwsh tests/Run-Tests.ps1 # full pyramid (layers 1-3)
Covers the module read/add/get/list paths, email + role validation (including case-sensitivity of role), duplicate rejection (case-insensitive), schema-version mismatch, atomic-write cleanup, and a concurrent-add race check that spawns two Start-ThreadJob racers across 5 rounds and asserts both entries survive every round. Plus CLI smoke: script parse + dispatcher wiring.

Scope note
team add / list / get only. remove / update / set-availability and role-* land in #631 on v4.2. Mothership sync of the local registry lives in #601. Deployment / hosting is documented in #576. This PR is intentionally minimal — the write surface downstream tickets need to exist.

Checklist

• Tests added or updated
• Docs updated (if behaviour changed)
• Linked issue exists
• Follows the contribution guide

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[tarikcosovic97]

@aselim31 ready for review.