feat(web): split SPA from oikos binary, require auth on every route

Phase 0 of plans/2026-07-12-wails-desktop-app.md. The control-room SPA
is no longer embedded (web/embed.go deleted); it's a standalone static
build served separately (make ui / make deploy-ui). The api process
adds CORS and drops the dev-open auth bypass — every route now needs a
real bearer token, including SSE (?token= query param, EventSource
can't set headers) and api's own /agent proxy to nomos (previously
unauthenticated by omission).

nomos was an unauthenticated client of api's /mcp and approval-decision
endpoints; closing dev-open would have broken it, so it now sends
Authorization: Bearer $OIKOS_MCP_BEARER_TOKEN on every call back to api.

SPA gets a runtime config module (config.ts) and a Config.svelte
first-launch/reconfigure page, reachable afterwards via a "Connection"
entry in the sidebar footer. Every fetch() in api.ts routes through
fetchWithAuth so the same build works same-origin (browser prod, Vite
dev proxy) or cross-origin (future Wails webview, remote access).

Six gaps found against the plan and the live Caddy topology while
implementing — documented in the plan's "Plan review" section, most
notably: api's own /agent mount was never behind combinedAuth (fixed),
and production's Authentik forward-auth needs a bearer-token bypass for
API routes that this repo's Caddyfile.oikos reference copy now has, but
the real dtoro/caddy-conf deploy does not yet.

Verified live: cross-origin static SPA + API, CORS, bearer auth, SSE
query-token auth, and localStorage persistence all confirmed working
in-browser. Full Go test suite and npm run build pass with no
regressions against the pre-change baseline.

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

compose/oikos/Dockerfile

@@ -1,14 +1,7 @@
-# Multi-stage Dockerfile for Oikos (ADR 0001: single binary)
-# Stage 1: build web UI
-FROM node:22-alpine AS ui-builder
-
-WORKDIR /web
-COPY web/package.json web/package-lock.json ./
-RUN npm ci
-COPY web/ ./
-RUN npm run build
-
-# Stage 2: build Go binary
+# Dockerfile for Oikos API server. The SPA is no longer embedded (see
+# plans/2026-07-12-wails-desktop-app.md 0.1) — it's built and deployed
+# separately as static files (see `make ui` / `make deploy-ui`).
+# Stage 1: build Go binary
 FROM golang:1.26-alpine AS builder
 
 RUN apk add --no-cache git ca-certificates
@@ -18,8 +11,6 @@ COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
-# Bring in the built SPA so //go:embed all:dist (web/embed.go) has real assets.
-COPY --from=ui-builder /web/dist ./web/dist
 
 RUN CGO_ENABLED=0 go build -o /oikos -tags timetzdata -ldflags="-s -w" ./cmd/oikos
 
@@ -31,6 +22,5 @@ RUN apk add --no-cache ca-certificates openssh-client-default
 COPY --from=builder /oikos /oikos
 COPY --from=builder /build/seeds /seeds
 COPY --from=builder /build/migrations /migrations
-# web/dist is embedded in the binary (web/embed.go) — no runtime copy needed.
 
 ENTRYPOINT ["/oikos"]