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/bits-ui/dist/bits/button/components/button.svelte

@@ -0,0 +1,27 @@
+<script lang="ts">
+	import type { ButtonRootProps } from "../types.js";
+
+	let {
+		href,
+		type,
+		children,
+		disabled = false,
+		ref = $bindable(null),
+		...restProps
+	}: ButtonRootProps = $props();
+</script>
+
+<svelte:element
+	this={href ? "a" : "button"}
+	data-button-root
+	type={href ? undefined : type}
+	href={href && !disabled ? href : undefined}
+	disabled={href ? undefined : disabled}
+	aria-disabled={href ? disabled : undefined}
+	role={href && disabled ? "link" : undefined}
+	tabindex={href && disabled ? -1 : 0}
+	bind:this={ref}
+	{...restProps}
+>
+	{@render children?.()}
+</svelte:element>

web/node_modules/bits-ui/dist/bits/button/components/button.svelte.d.ts

@@ -0,0 +1,4 @@
+import type { ButtonRootProps } from "../types.js";
+declare const Button: import("svelte").Component<ButtonRootProps, {}, "ref">;
+type Button = ReturnType<typeof Button>;
+export default Button;