feat: project cover art with AI generation, branding rename, RBAC fix, computation graph

- Add DALL-E cover art generation for projects (Azure OpenAI + standard OpenAI)
- CoverArtSection component with generate/upload/remove/focus-point controls
- Client-side image compression (10MB input → WebP/JPEG, max 1920px)
- DALL-E settings in admin panel (deployment, endpoint, API key)
- MCP assistant tools for cover art (generate_project_cover, remove_project_cover)
- Rename "Planarchy" → "plANARCHY" across all UI-facing text (13 files)
- Fix hardcoded canEdit={true} on project detail page — now checks user role
- Computation graph visualization (2D/3D) for calculation rules
- OG image and OpenGraph metadata

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/src/components/vacations/VacationClient.tsx

@@ -331,7 +331,7 @@ export function VacationClient() {
               <table className="w-full text-sm">
                 <thead>
                   <tr className="border-b border-gray-100 dark:border-gray-700 bg-gray-50 dark:bg-gray-900">
-                    <SortableColumnHeader label="Resource" field="resource" sortField={sortField} sortDir={sortDir} onSort={handleSort} />
+                    <SortableColumnHeader label="Resource" field="resource" sortField={sortField} sortDir={sortDir} onSort={handleSort} tooltip="The employee this vacation entry belongs to." />
                     <th className="px-3 py-3 text-xs font-medium text-gray-500 uppercase tracking-wider">
                       <span className="inline-flex items-center gap-0.5">
                         <button
@@ -344,8 +344,8 @@ export function VacationClient() {
                         <InfoTooltip content="ANNUAL = paid annual leave · SICK = sick leave · PUBLIC_HOLIDAY = public holiday · OTHER = other leave types." />
                       </span>
                     </th>
-                    <SortableColumnHeader label="Start" field="startDate" sortField={sortField} sortDir={sortDir} onSort={handleSort} />
-                    <SortableColumnHeader label="End" field="endDate" sortField={sortField} sortDir={sortDir} onSort={handleSort} />
+                    <SortableColumnHeader label="Start" field="startDate" sortField={sortField} sortDir={sortDir} onSort={handleSort} tooltip="First day of the leave period (inclusive). Shows a half-day indicator if applicable." />
+                    <SortableColumnHeader label="End" field="endDate" sortField={sortField} sortDir={sortDir} onSort={handleSort} tooltip="Last day of the leave period (inclusive)." />
                     <th className="px-3 py-3 text-xs font-medium text-gray-500 uppercase tracking-wider">
                       <span className="inline-flex items-center gap-0.5">
                         <button