docs(installer): lead with the installer now that it is released

v0.1.0 shipped on 2026-08-07, so every doc that said "not released yet"
was wrong the moment the cutover merged.

- INSTALL.md: replace the pre-release status banner. The installer is the
  path the guide leads with; Appendix A is reframed as supported-not-
  deprecated, for hosts that cannot run the binary, operators who want to
  place files themselves, and development from a working tree.
- PLAN.md: status is Shipped, both cutover gates recorded as met (incl.
  the Windows 1053 handshake bug the real SCM run found), Phase 5 table
  and 5.4 closed out.
- README.md: point anyone setting up a shard at INSTALL.md first.
- link/link-README.md: mark the pre-split snapshot as historical, so its
  deploy.ps1 instructions stop reading as the setup path.

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -14,6 +14,10 @@ installer/  docs for the installer that deploys a shard's bridge components
 ci/         cross-cutting CI/quality notes
 ```
 
+**Setting up a shard?** [`installer/INSTALL.md`](installer/INSTALL.md) is the operator guide, and
+the installer is the supported path: one binary deploys the plugin overlay, installs the uo-link
+sidecar as a service, and hands you the values the website needs.
+
 ### `website/`
 | Doc | What it covers |
 |---|---|
@@ -54,7 +58,7 @@ ci/         cross-cutting CI/quality notes
 ### `installer/`
 | Doc | What it covers |
 |---|---|
-| [INSTALL.md](installer/INSTALL.md) | **Operator guide** — installing Runic Gateway on a ServUO shard, connecting it to the website, and diagnosing it. Includes the by-hand path, which works today |
+| [INSTALL.md](installer/INSTALL.md) | **Start here to set up a shard** — the installer deploys the plugin overlay and the uo-link sidecar, registers the service, and connects it to the website. Appendix A is the same thing by hand, still supported |
 | [PLAN.md](installer/PLAN.md) | Installer design of record — phases, locked decisions, the bundle/compat-matrix model |
 
 ## Provenance