feat: Phase 1 — extract the client (web SPA + desktop) to dtoro/oikos-web

Problem: the hexagonal refactor churns the backend tree for nine more
phases; the UI delivery stack (web/ SPA, cmd/desktop Wails wrapper,
compose/web image) must move to its own repo first so doc/layout
rewrites land once on a backend-only tree.

Change:
- New repo git.hubris.network/dtoro/oikos-web (v0.33.0): web/, desktop/
  (updateURL repointed to oikos-web releases), compose/, own CI (web +
  desktop jobs), own deploy script (CI-green gate, TOCTOU guard,
  version-tagged images, prune-to-3), own webhook receiver on :9798 +
  launchd unit, own compose project publishing the same 8091:80.
- Cutover executed on mac-mini in order: oikos stack's web service
  stopped+removed, oikos-web project brought up on 8091; outer Caddy
  untouched (targets the published port) — serving + Authentik flow +
  /wails 404 quirk verified post-cutover.
- Stripped from oikos: web/, cmd/desktop/, compose/web/, desktop CI
  workflow, ci.yml web job, Makefile ui/desktop/desktop-package/install
  targets, the compose web service, oikos-web from deploy.sh's fallback
  prune list; wails + go-keyring dropped from go.mod, vendor synced.
- README / CONTRIBUTING / AGENTS.md / .agents dev+operations docs now
  point at the new repo; mbse + mascot design docs carry a path note.

Risk: production SPA serving depends on the new pipeline now; rollback
is versioned-image re-up of the old web service from a pre-split
checkout (port 8091). Desktop builds installed before the split still
check dtoro/oikos releases — one manual reinstall, noted in the
oikos-web release notes.

Verification: go vet, make test (race), make generate-check, golangci
(no new findings; baseline down 400→365); post-cutover curls —
localhost:8091 200, /wails/runtime.js 404, outer Caddy 302 Authentik.

docker-compose.yml

@@ -235,22 +235,10 @@ services:
       retries: 3
       start_period: 15s
 
-  # Control-room SPA — static build served behind Caddy. The outer
-  # production Caddy (caddy-conf repo, LXC 121) splits /api/*, /mcp,
-  # /agent/* off to api:8090 and sends everything else here; this
-  # container only serves static files with SPA-fallback routing.
-  web:
-    image: oikos-web:${OIKOS_VERSION:-latest}
-    build:
-      context: .
-      dockerfile: compose/web/Dockerfile
-    restart: unless-stopped
-    profiles: ["dev", "full"]
-    ports:
-      - "8091:80"
-    stop_signal: SIGTERM
-    mem_limit: 64m
-    cpus: 0.25
+  # The control-room SPA moved to its own repo (dtoro/oikos-web, Phase 1 of
+  # plans/2026-08-15-hexagonal-architecture.md) with its own compose project
+  # publishing the same host port 8091 — the outer Caddy targets the published
+  # port, so nothing here changes for routing.
 
   # Redis (required by Infisical — Phase 5)
   redis: