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/processor.js

@@ -0,0 +1,67 @@
+'use strict'
+
+let Document = require('./document')
+let LazyResult = require('./lazy-result')
+let NoWorkResult = require('./no-work-result')
+let Root = require('./root')
+
+class Processor {
+  constructor(plugins = []) {
+    this.version = '8.5.25'
+    this.plugins = this.normalize(plugins)
+  }
+
+  normalize(plugins) {
+    let normalized = []
+    for (let i of plugins) {
+      if (i.postcss === true) {
+        i = i()
+      } else if (i.postcss) {
+        i = i.postcss
+      }
+
+      if (typeof i === 'object' && Array.isArray(i.plugins)) {
+        normalized = normalized.concat(i.plugins)
+      } else if (typeof i === 'object' && i.postcssPlugin) {
+        normalized.push(i)
+      } else if (typeof i === 'function') {
+        normalized.push(i)
+      } else if (typeof i === 'object' && (i.parse || i.stringify)) {
+        if (process.env.NODE_ENV !== 'production') {
+          throw new Error(
+            'PostCSS syntaxes cannot be used as plugins. Instead, please use ' +
+              'one of the syntax/parser/stringifier options as outlined ' +
+              'in your PostCSS runner documentation.'
+          )
+        }
+      } else {
+        throw new Error(i + ' is not a PostCSS plugin')
+      }
+    }
+    return normalized
+  }
+
+  process(css, opts = {}) {
+    if (
+      !this.plugins.length &&
+      !opts.parser &&
+      !opts.stringifier &&
+      !opts.syntax
+    ) {
+      return new NoWorkResult(this, css, opts)
+    } else {
+      return new LazyResult(this, css, opts)
+    }
+  }
+
+  use(plugin) {
+    this.plugins = this.plugins.concat(this.normalize([plugin]))
+    return this
+  }
+}
+
+module.exports = Processor
+Processor.default = Processor
+
+Root.registerProcessor(Processor)
+Document.registerProcessor(Processor)