feat(desktop): implement workspace foundation + desktop-client skeleton

Plan 0 (workspaces): add workspaces + workspace_memberships schema, extend
JWT/Actor/claims with primary_workspace_id, seed default workspace per tenant,
thread workspace_id through tenant monitoring quota.

Plan A (desktop skeleton): new Electron app (apps/desktop-client) with main/
preload/renderer, shared Vue component package (packages/ui-shared), and server
surface — desktop client registration + token rotation + heartbeat, SSE task
event stream, desktop accounts/tasks/content handlers, publish job endpoint,
and supporting repositories, services, sqlc queries, and migrations.

Hard cutover per plan: remove browser-extension monitoring callback endpoints,
stub legacy media API in admin-web, and delete monitoring_callback_handler.go.

packages/ui-shared/src/components/index.ts

@@ -0,0 +1 @@
+export {};

packages/ui-shared/src/composables/index.ts

@@ -0,0 +1 @@
+export {};

packages/ui-shared/src/index.ts

@@ -0,0 +1,3 @@
+export * from "./tokens/index";
+export * from "./composables/index";
+export * from "./components/index";

packages/ui-shared/src/tokens/index.css

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+:root {
+  --geo-font-sans: "IBM Plex Sans", "Aptos", "Segoe UI Variable", "Segoe UI", sans-serif;
+  --geo-font-mono: "JetBrains Mono", "SFMono-Regular", "Cascadia Code", "Consolas", monospace;
+  --geo-color-bg-primary: #eef3f8;
+  --geo-color-bg-secondary: #e4ebf3;
+  --geo-color-bg-tertiary: #d6e1ec;
+  --geo-color-bg-elevated: rgba(255, 255, 255, 0.78);
+  --geo-color-bg-panel: rgba(247, 250, 253, 0.86);
+  --geo-color-text-primary: #111827;
+  --geo-color-text-secondary: #4b5563;
+  --geo-color-text-tertiary: #7b8794;
+  --geo-color-border: rgba(15, 23, 42, 0.08);
+  --geo-color-border-strong: rgba(15, 23, 42, 0.14);
+  --geo-color-brand: #0f766e;
+  --geo-color-brand-strong: #115e59;
+  --geo-color-brand-soft: rgba(15, 118, 110, 0.12);
+  --geo-color-success: #15803d;
+  --geo-color-success-soft: rgba(21, 128, 61, 0.12);
+  --geo-color-warn: #b45309;
+  --geo-color-warn-soft: rgba(180, 83, 9, 0.12);
+  --geo-color-danger: #b91c1c;
+  --geo-color-danger-soft: rgba(185, 28, 28, 0.12);
+  --geo-color-info: #2563eb;
+  --geo-color-info-soft: rgba(37, 99, 235, 0.12);
+  --geo-radius-sm: 12px;
+  --geo-radius-md: 20px;
+  --geo-radius-lg: 32px;
+  --geo-shadow-soft: 0 28px 60px rgba(15, 23, 42, 0.12);
+  --geo-shadow-card: 0 18px 36px rgba(15, 23, 42, 0.08);
+  --geo-shadow-edge: inset 0 1px 0 rgba(255, 255, 255, 0.6);
+}
+
+html[data-theme="dark"] {
+  --geo-color-bg-primary: #0a1015;
+  --geo-color-bg-secondary: #101820;
+  --geo-color-bg-tertiary: #16212c;
+  --geo-color-bg-elevated: rgba(16, 24, 32, 0.82);
+  --geo-color-bg-panel: rgba(10, 16, 21, 0.76);
+  --geo-color-text-primary: #ecf3fb;
+  --geo-color-text-secondary: #aebac7;
+  --geo-color-text-tertiary: #708090;
+  --geo-color-border: rgba(226, 232, 240, 0.08);
+  --geo-color-border-strong: rgba(226, 232, 240, 0.16);
+  --geo-color-brand: #46b7ab;
+  --geo-color-brand-strong: #63d0c4;
+  --geo-color-brand-soft: rgba(70, 183, 171, 0.14);
+  --geo-color-success: #5dd39e;
+  --geo-color-success-soft: rgba(93, 211, 158, 0.12);
+  --geo-color-warn: #f2a65a;
+  --geo-color-warn-soft: rgba(242, 166, 90, 0.14);
+  --geo-color-danger: #f36b7f;
+  --geo-color-danger-soft: rgba(243, 107, 127, 0.14);
+  --geo-color-info: #7aa2ff;
+  --geo-color-info-soft: rgba(122, 162, 255, 0.14);
+  --geo-shadow-soft: 0 32px 72px rgba(0, 0, 0, 0.42);
+  --geo-shadow-card: 0 18px 42px rgba(0, 0, 0, 0.28);
+  --geo-shadow-edge: inset 0 1px 0 rgba(255, 255, 255, 0.04);
+}
+
+html,
+body,
+#app {
+  min-height: 100%;
+}
+
+html {
+  color-scheme: light;
+}
+
+html[data-theme="dark"] {
+  color-scheme: dark;
+}
+
+body {
+  margin: 0;
+  font-family: var(--geo-font-sans);
+  background:
+    radial-gradient(circle at top left, rgba(15, 118, 110, 0.14), transparent 32%),
+    radial-gradient(circle at top right, rgba(37, 99, 235, 0.08), transparent 26%),
+    linear-gradient(180deg, var(--geo-color-bg-primary), var(--geo-color-bg-secondary));
+  color: var(--geo-color-text-primary);
+}
+
+* {
+  box-sizing: border-box;
+}
+
+button,
+input,
+textarea,
+select {
+  font: inherit;
+}
+
+code,
+pre {
+  font-family: var(--geo-font-mono);
+}

packages/ui-shared/src/tokens/index.ts

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+export const themeTokens = {
+  colorBgPrimary: "var(--geo-color-bg-primary)",
+  colorBgSecondary: "var(--geo-color-bg-secondary)",
+  colorTextPrimary: "var(--geo-color-text-primary)",
+  colorTextSecondary: "var(--geo-color-text-secondary)",
+  colorBorder: "var(--geo-color-border)",
+  colorBrand: "var(--geo-color-brand)",
+  colorSuccess: "var(--geo-color-success)",
+  colorWarn: "var(--geo-color-warn)",
+  colorDanger: "var(--geo-color-danger)",
+} as const;
+
+export type ThemeTokenKey = keyof typeof themeTokens;