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/postcss/lib/stringifier.d.ts

@@ -0,0 +1,45 @@
+import {
+  AnyNode,
+  AtRule,
+  Builder,
+  Comment,
+  Container,
+  Declaration,
+  Document,
+  Root,
+  Rule
+} from './postcss.js'
+
+declare namespace Stringifier {
+  export { Stringifier_ as default }
+}
+
+declare class Stringifier_ {
+  builder: Builder
+  constructor(builder: Builder)
+  atrule(node: AtRule, semicolon?: boolean): void
+  beforeAfter(node: AnyNode, detect: 'after' | 'before'): string
+  block(node: AnyNode, start: string): void
+  body(node: Container): void
+  comment(node: Comment): void
+  decl(node: Declaration, semicolon?: boolean): void
+  document(node: Document): void
+  raw(node: AnyNode, own: null | string, detect?: string): boolean | string
+  rawBeforeClose(root: Root): string | undefined
+  rawBeforeComment(root: Root, node: Comment): string | undefined
+  rawBeforeDecl(root: Root, node: Declaration): string | undefined
+  rawBeforeOpen(root: Root): string | undefined
+  rawBeforeRule(root: Root): string | undefined
+  rawColon(root: Root): string | undefined
+  rawEmptyBody(root: Root): string | undefined
+  rawIndent(root: Root): string | undefined
+  rawSemicolon(root: Root): boolean | undefined
+  rawValue(node: AnyNode, prop: string): number | string
+  root(node: Root): void
+  rule(node: Rule): void
+  stringify(node: AnyNode, semicolon?: boolean): void
+}
+
+declare class Stringifier extends Stringifier_ {}
+
+export = Stringifier