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/eslint/lib/shared/serialization.js

@@ -0,0 +1,78 @@
+/**
+ * @fileoverview Serialization utils.
+ * @author Bryan Mishkin
+ */
+
+"use strict";
+
+/**
+ * Check if a value is a primitive or plain object created by the Object constructor.
+ * @param {any} val the value to check
+ * @returns {boolean} true if so
+ * @private
+ */
+function isSerializablePrimitiveOrPlainObject(val) {
+	return (
+		val === null ||
+		typeof val === "string" ||
+		typeof val === "boolean" ||
+		typeof val === "number" ||
+		(typeof val === "object" && val.constructor === Object) ||
+		Array.isArray(val)
+	);
+}
+
+/**
+ * Check if a value is serializable.
+ * Functions or objects like RegExp cannot be serialized by JSON.stringify().
+ * Inspired by: https://stackoverflow.com/questions/30579940/reliable-way-to-check-if-objects-is-serializable-in-javascript
+ * @param {any} val The value
+ * @param {Set<Object>} seenObjects Objects already seen in this path from the root object.
+ * @returns {boolean} `true` if the value is serializable
+ */
+function isSerializable(val, seenObjects = new Set()) {
+	if (!isSerializablePrimitiveOrPlainObject(val)) {
+		return false;
+	}
+	if (typeof val === "object" && val !== null) {
+		if (seenObjects.has(val)) {
+			/*
+			 * Since this is a depth-first traversal, encountering
+			 * the same object again means there is a circular reference.
+			 * Objects with circular references are not serializable.
+			 */
+			return false;
+		}
+		for (const property in val) {
+			if (Object.hasOwn(val, property)) {
+				if (!isSerializablePrimitiveOrPlainObject(val[property])) {
+					return false;
+				}
+				if (
+					typeof val[property] === "object" &&
+					val[property] !== null
+				) {
+					if (
+						/*
+						 * We're creating a new Set of seen objects because we want to
+						 * ensure that `val` doesn't appear again in this path, but it can appear
+						 * in other paths. This allows for reusing objects in the graph, as long as
+						 * there are no cycles.
+						 */
+						!isSerializable(
+							val[property],
+							new Set([...seenObjects, val]),
+						)
+					) {
+						return false;
+					}
+				}
+			}
+		}
+	}
+	return true;
+}
+
+module.exports = {
+	isSerializable,
+};