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/browser/dist/errors.js

@@ -0,0 +1,57 @@
+class YAMLError extends Error {
+    constructor(name, pos, code, message) {
+        super();
+        this.name = name;
+        this.code = code;
+        this.message = message;
+        this.pos = pos;
+    }
+}
+class YAMLParseError extends YAMLError {
+    constructor(pos, code, message) {
+        super('YAMLParseError', pos, code, message);
+    }
+}
+class YAMLWarning extends YAMLError {
+    constructor(pos, code, message) {
+        super('YAMLWarning', pos, code, message);
+    }
+}
+const prettifyError = (src, lc) => (error) => {
+    if (error.pos[0] === -1)
+        return;
+    error.linePos = error.pos.map(pos => lc.linePos(pos));
+    const { line, col } = error.linePos[0];
+    error.message += ` at line ${line}, column ${col}`;
+    let ci = col - 1;
+    let lineStr = src
+        .substring(lc.lineStarts[line - 1], lc.lineStarts[line])
+        .replace(/[\n\r]+$/, '');
+    // Trim to max 80 chars, keeping col position near the middle
+    if (ci >= 60 && lineStr.length > 80) {
+        const trimStart = Math.min(ci - 39, lineStr.length - 79);
+        lineStr = '…' + lineStr.substring(trimStart);
+        ci -= trimStart - 1;
+    }
+    if (lineStr.length > 80)
+        lineStr = lineStr.substring(0, 79) + '…';
+    // Include previous line in context if pointing at line start
+    if (line > 1 && /^ *$/.test(lineStr.substring(0, ci))) {
+        // Regexp won't match if start is trimmed
+        let prev = src.substring(lc.lineStarts[line - 2], lc.lineStarts[line - 1]);
+        if (prev.length > 80)
+            prev = prev.substring(0, 79) + '…\n';
+        lineStr = prev + lineStr;
+    }
+    if (/[^ ]/.test(lineStr)) {
+        let count = 1;
+        const end = error.linePos[1];
+        if (end?.line === line && end.col > col) {
+            count = Math.max(1, Math.min(end.col - col, 80 - ci));
+        }
+        const pointer = ' '.repeat(ci) + '^'.repeat(count);
+        error.message += `:\n\n${lineStr}\n${pointer}\n`;
+    }
+};
+
+export { YAMLError, YAMLParseError, YAMLWarning, prettifyError };