refactor: remove deprecated weekly summary components and related services

- Deleted `WeeklySummaryClient`, `VelocityMetrics`, `PeriodSelector`, and associated services to streamline the codebase.
- Removed the `weekly-summary` API route and related PDF export functionality, as these features are no longer in use.
- Updated `TODO.md` to reflect the removal of these components and their functionalities.

components/ui/Header.tsx

@@ -53,7 +53,6 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
     { href: '/', label: 'Dashboard' },
     { href: '/kanban', label: 'Kanban' },
     { href: '/daily', label: 'Daily' },
-    { href: '/weekly-summary', label: 'Hebdo' },
     { href: '/weekly-manager', label: 'Manager' },
     ...(isJiraConfigured ? [{ href: '/jira-dashboard', label: `Jira${jiraConfig?.projectKey ? ` (${jiraConfig.projectKey})` : ''}` }] : []),
     { href: '/settings', label: 'Settings' }