feat(deploy): containerize the web UI as its own compose service

The SPA-from-binary split (0c0f35a) left `make deploy-ui` pointing at a
deploy path that was never actually wired up: scp to a "mac-mini" SSH
host that doesn't resolve from itself, a /var/www/oikos-ui/ that doesn't
exist, and `systemctl reload caddy` on a box with no Caddy installed at
all (not brew, not a container, nothing on 80/443).

Add a `web` service (compose/web/Dockerfile: node build -> caddy:2-alpine
static + SPA-fallback serving) to docker-compose.yml so the UI deploys
through the same push-to-main -> webhook -> docker compose build/up
pipeline the rest of the stack already uses, instead of a manual
scp/ssh step. Drop the broken `deploy-ui` Makefile target; `make ui`
stays as a local build sanity-check.

Update the reference Caddy config (compose/caddy/Caddyfile.oikos) to
reverse_proxy the new :8091 service instead of reading static files off
local disk, and fill in the <mac-mini-mesh-ip> placeholders with the
actual LAN IP (192.168.178.182 — the LXC and mac-mini subnets are
routed). This file is a reference only; the real caddy-conf repo change
is applied separately after review.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docker-compose.yml

@@ -2,9 +2,11 @@
 # Usage: docker compose up -d postgres  (just the DB)
 #        make dev                     (full dev stack)
 #
-# The SPA isn't part of this stack — it's a standalone static build served
-# separately (`make ui`, `npm run dev` in web/), not embedded in the oikos
-# image. See plans/2026-07-12-wails-desktop-app.md 0.1/0.6.
+# The SPA isn't embedded in the oikos binary (see
+# plans/2026-07-12-wails-desktop-app.md 0.1/0.6) but it IS part of this
+# stack as its own `web` service (compose/web/Dockerfile), so it deploys
+# through the same push-to-main pipeline as everything else. `npm run dev`
+# in web/ is still the fast local-iteration path.
 
 services:
   postgres:
@@ -145,6 +147,19 @@ services:
     stop_signal: SIGTERM
     stop_grace_period: 10s
 
+  # 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:
+    build:
+      context: .
+      dockerfile: compose/web/Dockerfile
+    profiles: ["dev", "full"]
+    ports:
+      - "8091:80"
+    stop_signal: SIGTERM
+
   # Redis (required by Infisical — Phase 5)
   redis:
     image: redis:7-alpine