feat(gui-v2): port WorkspaceSwitcher to TypeScript

Ports crewli-starter WorkspaceSwitcher into the Crewli SPA as production
TypeScript: PrimeVue Popover replaces the manual click-outside listener,
data is derived from useAuthStore/useOrganisationStore (no new store), gradient
pairs are deterministic via a new pure util with full Vitest coverage.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/app/src/utils/v2/gradient.ts

@@ -0,0 +1,39 @@
+/**
+ * computeOrgGradient — deterministic gradient pair for an organisation.
+ *
+ * Maps an org `id` string to one of 8 teal-adjacent colour pairs via a
+ * simple djb2-style character-code hash.  Same id always returns the
+ * same pair; no external dependencies.
+ *
+ * Palette rationale: teal / cyan / emerald / sea-green family to stay
+ * on-brand with Crewli's teal primary.  Each tuple is [from, to] for a
+ * 135° linear gradient (darker "to" keeps depth on the logo square).
+ */
+
+/** Exported so tests can assert membership without hard-coding values. */
+export const GRADIENT_PALETTE: [string, string][] = [
+  ['#0d9488', '#0f766e'], // teal-600 → teal-700
+  ['#0891b2', '#0e7490'], // cyan-600 → cyan-700
+  ['#059669', '#047857'], // emerald-600 → emerald-700
+  ['#10b981', '#059669'], // emerald-500 → emerald-600
+  ['#0284c7', '#0369a1'], // sky-600 → sky-700
+  ['#14b8a6', '#0d9488'], // teal-500 → teal-600
+  ['#06b6d4', '#0891b2'], // cyan-500 → cyan-600
+  ['#34d399', '#10b981'], // emerald-400 → emerald-500
+]
+
+/**
+ * Returns a `[fromHex, toHex]` colour pair deterministically derived
+ * from `id`.  Handles empty string (hash stays 0; maps to palette[0]).
+ */
+export function computeOrgGradient(id: string): [string, string] {
+  // djb2-style hash: accumulate across char codes
+  let hash = 5381
+  for (let i = 0; i < id.length; i++) {
+    // Equivalent to hash * 33 ^ charCode, kept 32-bit safe via >>> 0
+    hash = ((hash << 5) + hash + id.charCodeAt(i)) >>> 0
+  }
+  const index = hash % GRADIENT_PALETTE.length
+
+  return GRADIENT_PALETTE[index]
+}