feat: add flexible capability-based RBAC with per-tenant customization

Introduces a capability layer on top of existing roles that controls
feature visibility and access. Capabilities follow an area.feature.action
taxonomy (~35 capabilities) with sensible defaults per role. Tenant admins
can customize via grant/revoke overrides stored in org settings JSONB.

Key changes:
- Add vice_president role to DB schema
- Backend: capability constants, resolution logic, CapabilityGuard (global),
  @RequireCapability decorator on all 16 tenant controllers
- Frontend: permission hooks (useCanEdit, useHasCapability), CapabilityGate
  component, sidebar filtering by capability, all 17 pages migrated from
  useIsReadOnly to capability-based checks
- New admin UI: /settings/permissions matrix page for per-tenant role
  customization with grant/revoke delta model
- GET /organizations/my-capabilities endpoint for capability refresh
- Validation of permissionOverrides in settings updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/modules/units/units.controller.ts

@@ -2,6 +2,7 @@ import { Controller, Get, Post, Put, Delete, Body, Param, Res, UseGuards } from
 import { ApiTags, ApiBearerAuth } from '@nestjs/swagger';
 import { Response } from 'express';
 import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
+import { RequireCapability } from '../../common/decorators/capability.decorator';
 import { UnitsService } from './units.service';
 
 @ApiTags('units')
@@ -12,9 +13,11 @@ export class UnitsController {
   constructor(private unitsService: UnitsService) {}
 
   @Get()
+  @RequireCapability('assessments.units.view')
   findAll() { return this.unitsService.findAll(); }
 
   @Get('export')
+  @RequireCapability('assessments.units.view')
   async exportCSV(@Res() res: Response) {
     const csv = await this.unitsService.exportCSV();
     res.set({ 'Content-Type': 'text/csv', 'Content-Disposition': 'attachment; filename="units.csv"' });
@@ -22,17 +25,22 @@ export class UnitsController {
   }
 
   @Get(':id')
+  @RequireCapability('assessments.units.view')
   findOne(@Param('id') id: string) { return this.unitsService.findOne(id); }
 
   @Post('import')
+  @RequireCapability('assessments.units.edit')
   importCSV(@Body() rows: any[]) { return this.unitsService.importCSV(rows); }
 
   @Post()
+  @RequireCapability('assessments.units.edit')
   create(@Body() dto: any) { return this.unitsService.create(dto); }
 
   @Put(':id')
+  @RequireCapability('assessments.units.edit')
   update(@Param('id') id: string, @Body() dto: any) { return this.unitsService.update(id, dto); }
 
   @Delete(':id')
+  @RequireCapability('assessments.units.edit')
   delete(@Param('id') id: string) { return this.unitsService.delete(id); }
 }