docs: freeze Phase 1 org-ui single-source dual-delivery contract

[XYAIStudio]

Summary

Phase 1 freezes the openXYOS → Octop/FreeOS organization-module merge contract. Docs and cross-links only — no UI moves, no installer changes, no app code.

Product rules this PR records (non-negotiable):

• Organization module code is the single source of truth.
• openXYOS web pages become sub-UIs under FreeOS Dashboard /organization/..., not a second always-on system.
• The same source must still generate a standalone openXYOS web for customer self-host (commercial upsell).
• One installer by default (no mandatory Node sidecar). Sidecar stays opt-in (FREEOS_ORG_SIDECAR / SHIP_OPENXYOS_RUNTIME).
• Do not replace the FreeOS/Octop agent chat runtime with openXYOS Chat.

What landed

File	Role
docs/adr/003-org-ui-single-source-dual-delivery.md	Accepted ADR: shell-agnostic org-ui + thin Dashboard adapter + freeos org export-standalone
docs/org-merge-plan.md	Phases 0–5, overlap matrix, package layout, API ownership, IdentityBridge, Phase 2 acceptance
docs/adr/README.md	ADR index

Light pointers only in docs/architecture-integration.md (Related + capability-map target), docs/architecture.md See also, and a one-line target-architecture note in README_CN.md.

Numbering: docs/adr/002-database-backends.md already exists, so this decision is ADR 003 (not 002).

Alternatives rejected (ADR)

• Permanent dual process (host + always-on Node sidecar)
• iframe forever (:3780 inside /organization)
• Duplicate, hand-maintained standalone openXYOS

Phase 2 (not in this PR)

Announcements vertical slice, with acceptance:

1. Dashboard route under /organization/...
2. No iframe / no second port for that page
3. Same page components usable in freeos org export-standalone output

Test plan

• Docs-only; no make all / app tests required for this change.
• Verified relative links among the new ADR, merge plan, ADR index, and the three lightly edited docs.
• Confirmed git diff contains markdown only.

Target branch

• Base is main — this repository has no develop branch; FreeOS 0.0.2: in-host Organization, optional openXYOS sidecar #55 (in-host Organization) already landed on main.