docs(adr): ADR-0123 — layered master data, template/override linkage and the resolution organization (#4585)

Discharges the ADR-0105 D10 reservation ("mechanics to be detailed in a
follow-up ADR"). Status: Proposed — decision-ready material, no code.

The draft is built on three measurements taken against main, none of which
existed when D10 was reserved:

- Layer 0 under `group` is `{ organization_id: { $in: accessible_org_ids } }`
  (tenant-layer.ts:139-143), which lowers to SQL `IN (...)` and is NULL-false,
  while the SQL driver's own tenant chokepoint carries the opposite NULL
  carve-out (sql-driver.ts:6369, :6382). An org-less "read-shared template"
  row is therefore actively excluded today, and W1/W2 mean no Layer 1
  mechanism can restore it.
- D2 demoted the active organization out of the read path, so "org override
  wins" has no organization to win for. Resolution needs a resolution
  organization, and the union wall removed the obvious one.
- D6 red line 1 is an error-severity lint (validate-org-axis-red-lines.ts):
  an authored policy or sharing rule reading `parent_organization_id` fails
  at authoring time, so resolution must be engine machinery, not metadata.

Decisions: D1 object-level `layered` that refuses outside the `group` posture;
D2 natural-key linkage over a row-id lookup, riding ADR-0120's
`unique: 'organization'`; D3 org-less template plus one narrow, declared,
read-only opening in Layer 0 (with the flat-vs-rooted fork left to the
maintainer); D4 no implicit collapse on read, resolution explicit and
per-organization for a union reader; D5 集团统管/分级/自由 declared per object
and enforced on write, not resolved away on read; D6 reuse of D9's
`$root`/`$parent` and "shares a root"; D7 the open/commercial line stated
per cloud ADR-0016 and D12's code-vs-activation amendment, including the
boot refusal; D8 named non-goals.

Appendix A records the cloud-side inputs (cloud#874, #2937, #881/#884) that
were unreadable from the drafting session as inputs-to-verify rather than
as facts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018YpzLzyoGkM4rspmBeGYMW

Author: claude