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/which/bin/node-which

@@ -0,0 +1,52 @@
+#!/usr/bin/env node
+var which = require("../")
+if (process.argv.length < 3)
+  usage()
+
+function usage () {
+  console.error('usage: which [-as] program ...')
+  process.exit(1)
+}
+
+var all = false
+var silent = false
+var dashdash = false
+var args = process.argv.slice(2).filter(function (arg) {
+  if (dashdash || !/^-/.test(arg))
+    return true
+
+  if (arg === '--') {
+    dashdash = true
+    return false
+  }
+
+  var flags = arg.substr(1).split('')
+  for (var f = 0; f < flags.length; f++) {
+    var flag = flags[f]
+    switch (flag) {
+      case 's':
+        silent = true
+        break
+      case 'a':
+        all = true
+        break
+      default:
+        console.error('which: illegal option -- ' + flag)
+        usage()
+    }
+  }
+  return false
+})
+
+process.exit(args.reduce(function (pv, current) {
+  try {
+    var f = which.sync(current, { all: all })
+    if (all)
+      f = f.join('\n')
+    if (!silent)
+      console.log(f)
+    return pv;
+  } catch (e) {
+    return 1;
+  }
+}, 0))