DOCFIX-154/155/156: Stage 2/3/5 runbooks -- Office1 standup, DC substrate, per-DC bundle ...

Three DC-DC runbooks authored in parallel this evening:
- Stage 2 (Office1 headend standup): MAAS-region/NetBox/GitBucket/Tailscale,
  each VM-creation step forking an explicit OpenTofu-blocked vs manual-debt
  path rather than picking one silently. Flags a real gap: no Office1-local
  network is modeled in opentofu/.
- Stage 3 (OpenTofu builds each DC substrate): DC1-first, DC2 hard-gated on
  NetBox literals. Walks every open decision (node sizing, MAAS zone/pool,
  config.xml tokens, netem params) and stops rather than inventing values.
- Stage 5 (Juju controller + bundle, per DC): describes adapting the
  existing phase-01..08 loop to run twice, not duplicating it. Mandates the
  $DC selector convention (DOCFIX-151) before every adapted command block.
  Surfaces the undesigned IPv6 family-matrix overlay as blocking work.

All three: not yet executed (prep-only session, no live infrastructure
reachable tonight); repo-lint 0 fail/1 documented warn.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QrcJx8TUar7pYAvpGJw57A