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.

web/node_modules/dunder-proto/set.js

@@ -0,0 +1,35 @@
+'use strict';
+
+var callBind = require('call-bind-apply-helpers');
+var gOPD = require('gopd');
+var $TypeError = require('es-errors/type');
+
+/** @type {{ __proto__?: object | null }} */
+var obj = {};
+try {
+	obj.__proto__ = null; // eslint-disable-line no-proto
+} catch (e) {
+	if (!e || typeof e !== 'object' || !('code' in e) || e.code !== 'ERR_PROTO_ACCESS') {
+		throw e;
+	}
+}
+
+var hasProtoMutator = !('toString' in obj);
+
+// eslint-disable-next-line no-extra-parens
+var desc = gOPD && gOPD(Object.prototype, /** @type {keyof typeof Object.prototype} */ ('__proto__'));
+
+/** @type {import('./set')} */
+module.exports = hasProtoMutator && (
+// eslint-disable-next-line no-extra-parens
+	(!!desc && typeof desc.set === 'function' && /** @type {import('./set')} */ (callBind([desc.set])))
+	|| /** @type {import('./set')} */ function setDunder(object, proto) {
+		// this is node v0.10 or older, which doesn't have Object.setPrototypeOf and has undeniable __proto__
+		if (object == null) { // eslint-disable-line eqeqeq
+			throw new $TypeError('set Object.prototype.__proto__ called on null or undefined');
+		}
+		// eslint-disable-next-line no-proto, no-param-reassign, no-extra-parens
+		/** @type {{ __proto__?: object | null }} */ (object).__proto__ = proto;
+		return proto;
+	}
+);