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/dompurify/src/regexp.ts

@@ -0,0 +1,24 @@
+import { seal } from './utils.js';
+
+export const MUSTACHE_EXPR = seal(/{{[\w\W]*|^[\w\W]*}}/g);
+export const ERB_EXPR = seal(/<%[\w\W]*|^[\w\W]*%>/g);
+export const TMPLIT_EXPR = seal(/\${[\w\W]*/g);
+export const DATA_ATTR = seal(/^data-[\-\w.\u00B7-\uFFFF]+$/); // eslint-disable-line no-useless-escape
+export const ARIA_ATTR = seal(/^aria-[\-\w]+$/); // eslint-disable-line no-useless-escape
+export const IS_ALLOWED_URI = seal(
+  /^(?:(?:(?:f|ht)tps?|mailto|tel|callto|sms|cid|xmpp|matrix):|[^a-z]|[a-z+.\-]+(?:[^a-z+.\-:]|$))/i // eslint-disable-line no-useless-escape
+);
+export const IS_SCRIPT_OR_DATA = seal(/^(?:\w+script|data):/i);
+export const ATTR_WHITESPACE = seal(
+  /[\u0000-\u0020\u00A0\u1680\u180E\u2000-\u2029\u205F\u3000]/g // eslint-disable-line no-control-regex
+);
+export const DOCTYPE_NAME = seal(/^html$/i);
+export const CUSTOM_ELEMENT = seal(/^[a-z][.\w]*(-[.\w]+)+$/i);
+
+// Markup-significant character probes used by _sanitizeElements.
+// Shared module-level instances are safe despite the sticky /g flags:
+// unapply() resets lastIndex for RegExp receivers before every call.
+export const ELEMENT_MARKUP_PROBE = seal(/<[/\w!]/g);
+export const COMMENT_MARKUP_PROBE = seal(/<[/\w]/g);
+export const FALLBACK_TAG_CLOSE = seal(/<\/no(script|embed|frames)/i);
+export const SELF_CLOSING_TAG = seal(/\/>/i);