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/runed/dist/utilities/use-intersection-observer/index.d.ts

@@ -0,0 +1 @@
+export * from "./use-intersection-observer.svelte.js";

web/node_modules/runed/dist/utilities/use-intersection-observer/index.js

@@ -0,0 +1 @@
+export * from "./use-intersection-observer.svelte.js";

web/node_modules/runed/dist/utilities/use-intersection-observer/use-intersection-observer.svelte.d.ts

@@ -0,0 +1,28 @@
+import type { MaybeElementGetter, MaybeGetter } from "../../internal/types.js";
+import { type ConfigurableWindow } from "../../internal/configurable-globals.js";
+export interface UseIntersectionObserverOptions extends Omit<IntersectionObserverInit, "root">, ConfigurableWindow {
+    /**
+     * Whether to start the observer immediately upon creation. If set to `false`, the observer
+     * will only start observing when `resume()` is called.
+     *
+     * @defaultValue true
+     */
+    immediate?: boolean;
+    /**
+     * The root document/element to use as the bounding box for the intersection.
+     */
+    root?: MaybeElementGetter;
+}
+/**
+ * Watch for intersection changes of a target element.
+ *
+ * @see https://runed.dev/docs/utilities/useIntersectionObserver
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver IntersectionObserver MDN
+ */
+export declare function useIntersectionObserver(target: MaybeGetter<HTMLElement | HTMLElement[] | null | undefined>, callback: IntersectionObserverCallback, options?: UseIntersectionObserverOptions): {
+    readonly isActive: boolean;
+    stop: () => void;
+    pause(): void;
+    resume(): void;
+};
+export type UseIntersectionObserverReturn = ReturnType<typeof useIntersectionObserver>;

web/node_modules/runed/dist/utilities/use-intersection-observer/use-intersection-observer.svelte.js

@@ -0,0 +1,49 @@
+import { extract } from "../extract/extract.svelte.js";
+import { get } from "../../internal/utils/get.js";
+import { defaultWindow } from "../../internal/configurable-globals.js";
+/**
+ * Watch for intersection changes of a target element.
+ *
+ * @see https://runed.dev/docs/utilities/useIntersectionObserver
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver IntersectionObserver MDN
+ */
+export function useIntersectionObserver(target, callback, options = {}) {
+    const { root, rootMargin = "0px", threshold = 0.1, immediate = true, window = defaultWindow, } = options;
+    let isActive = $state(immediate);
+    let observer;
+    const targets = $derived.by(() => {
+        const value = extract(target);
+        return new Set(value ? (Array.isArray(value) ? value : [value]) : []);
+    });
+    const stop = $effect.root(() => {
+        $effect(() => {
+            if (!targets.size || !isActive || !window)
+                return;
+            observer = new window.IntersectionObserver(callback, {
+                rootMargin,
+                root: get(root),
+                threshold,
+            });
+            for (const el of targets)
+                observer.observe(el);
+            return () => {
+                observer?.disconnect();
+            };
+        });
+    });
+    $effect(() => {
+        return stop;
+    });
+    return {
+        get isActive() {
+            return isActive;
+        },
+        stop,
+        pause() {
+            isActive = false;
+        },
+        resume() {
+            isActive = true;
+        },
+    };
+}