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/dist/mascot/LICENSE-eggs.txt

@@ -0,0 +1,20 @@
+Eggs
+By Onocentaur
+https://onocentaur.itch.io
+March 2021
+
+Description 
+350+ pixel art eggs for your next virtual pet/match 3/farming/holiday themed game.
+
+This pack contains:
+	⁃	Over 350 16x16px eggs.
+	⁃	32 egg designs, 11 color variants.
+	⁃	2 different cracking animations for each egg.
+	⁃	Spritesheets for each color variant and cracking pattern.
+	⁃	Transparent PNGs.
+	⁃	Template files so you can color your own eggs.
+	⁃	Bonus: Letter & Number eggs.
+	⁃	Bonus: Incubator assets (nesting box and toggle-able lamp).
+	⁃	Bonus: 12 Animal assets.  
+
+Free to use for personal & professional projects.  Attribution appreciated.  If you use these assets in your project, let me know!  I look forward to seeing what you make.