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/yaml/dist/schema/yaml-1.1/merge.js

@@ -0,0 +1,71 @@
+'use strict';
+
+var identity = require('../../nodes/identity.js');
+var Scalar = require('../../nodes/Scalar.js');
+
+// If the value associated with a merge key is a single mapping node, each of
+// its key/value pairs is inserted into the current mapping, unless the key
+// already exists in it. If the value associated with the merge key is a
+// sequence, then this sequence is expected to contain mapping nodes and each
+// of these nodes is merged in turn according to its order in the sequence.
+// Keys in mapping nodes earlier in the sequence override keys specified in
+// later mapping nodes. -- http://yaml.org/type/merge.html
+const MERGE_KEY = '<<';
+const merge = {
+    identify: value => value === MERGE_KEY ||
+        (typeof value === 'symbol' && value.description === MERGE_KEY),
+    default: 'key',
+    tag: 'tag:yaml.org,2002:merge',
+    test: /^<<$/,
+    resolve: () => Object.assign(new Scalar.Scalar(Symbol(MERGE_KEY)), {
+        addToJSMap: addMergeToJSMap
+    }),
+    stringify: () => MERGE_KEY
+};
+const isMergeKey = (ctx, key) => (merge.identify(key) ||
+    (identity.isScalar(key) &&
+        (!key.type || key.type === Scalar.Scalar.PLAIN) &&
+        merge.identify(key.value))) &&
+    ctx?.doc.schema.tags.some(tag => tag.tag === merge.tag && tag.default);
+function addMergeToJSMap(ctx, map, value) {
+    const source = resolveAliasValue(ctx, value);
+    if (identity.isSeq(source))
+        for (const it of source.items)
+            mergeValue(ctx, map, it);
+    else if (Array.isArray(source))
+        for (const it of source)
+            mergeValue(ctx, map, it);
+    else
+        mergeValue(ctx, map, source);
+}
+function mergeValue(ctx, map, value) {
+    const source = resolveAliasValue(ctx, value);
+    if (!identity.isMap(source))
+        throw new Error('Merge sources must be maps or map aliases');
+    const srcMap = source.toJSON(null, ctx, Map);
+    for (const [key, value] of srcMap) {
+        if (map instanceof Map) {
+            if (!map.has(key))
+                map.set(key, value);
+        }
+        else if (map instanceof Set) {
+            map.add(key);
+        }
+        else if (!Object.prototype.hasOwnProperty.call(map, key)) {
+            Object.defineProperty(map, key, {
+                value,
+                writable: true,
+                enumerable: true,
+                configurable: true
+            });
+        }
+    }
+    return map;
+}
+function resolveAliasValue(ctx, value) {
+    return ctx && identity.isAlias(value) ? value.resolve(ctx.doc, ctx) : value;
+}
+
+exports.addMergeToJSMap = addMergeToJSMap;
+exports.isMergeKey = isMergeKey;
+exports.merge = merge;