i18n: Add 29 missing translation keys (DE + EN) and fix 19 hardcoded strings

Added missing i18n keys:
- action.upload, label.selected, student_portal.daily_inspiration
- auth.* (back_to_login, cancel, forgot_check_inbox, forgot_email_sent,
  forgot_password_desc, password_weak/fair/good/strong, send_reset_link)
- attendance.daily_timeline, competition.unlimited
- date.* (jan through dec - short month names)
- drawing.bg_type, drawing.canvas_label

Fixed 19 hardcoded English strings:
- admin/compliance-overview: 5 strings (dashboard title, status, policies, log)
- admin/exam-proctoring: 3 strings (proctoring, sessions)
- admin/signage: 1 string (emergency signage)
- compliance-wizard: 3 strings (retention periods, checklist, complete)
- dashboard-customizer: 1 string (add widget)
- data-import-export: 2 strings (best practices, export regularly)
- district-management: 1 string (access denied)
- exam-session-monitor: 1 string (exam mode active)
- professional-calendar: 1 string (fixed 'Create Neues Ereignis' typo)
- ui/sidebar: 1 string (toggle sidebar)

src/lib/i18n.ts

@@ -819,6 +819,35 @@ const de: TranslationDict = {
   'polish.nav_insights': 'Erkenntnisse',
   'polish.nav_administration': 'Verwaltung',
   'nav.ai-studio': 'KI-Studio',
+  'action.upload': 'Hochladen',
+  'attendance.daily_timeline': 'Tagesverlauf',
+  'auth.back_to_login': 'Zurück zum Login',
+  'auth.cancel': 'Abbrechen',
+  'auth.forgot_check_inbox': 'Bitte überprüfen Sie Ihr Postfach',
+  'auth.forgot_email_sent': 'E-Mail zum Zurücksetzen des Passworts wurde gesendet',
+  'auth.forgot_password_desc': 'Geben Sie Ihre E-Mail-Adresse ein, um Ihr Passwort zurückzusetzen',
+  'auth.password_weak': 'Schwach',
+  'auth.password_fair': 'Ausreichend',
+  'auth.password_good': 'Gut',
+  'auth.password_strong': 'Stark',
+  'auth.send_reset_link': 'Link zum Zurücksetzen senden',
+  'competition.unlimited': 'Unbegrenzt',
+  'date.jan': 'Jan',
+  'date.feb': 'Feb',
+  'date.mar': 'Mär',
+  'date.apr': 'Apr',
+  'date.may': 'Mai',
+  'date.jun': 'Jun',
+  'date.jul': 'Jul',
+  'date.aug': 'Aug',
+  'date.sep': 'Sep',
+  'date.oct': 'Okt',
+  'date.nov': 'Nov',
+  'date.dec': 'Dez',
+  'drawing.bg_type': 'Hintergrundtyp',
+  'drawing.canvas_label': 'Zeichenfläche',
+  'label.selected': 'Ausgewählt',
+  'student_portal.daily_inspiration': 'Tägliche Inspiration',
   'polish.nav_setup': 'Einrichtung',
   'polish.nav_teaching': 'Unterricht',
   'polish.nav_analysis': 'Analyse',
@@ -7428,6 +7457,35 @@ const en: TranslationDict = {
   'polish.nav_insights': 'Insights',
   'polish.nav_administration': 'Administration',
   'nav.ai-studio': 'AI Studio',
+  'action.upload': 'Upload',
+  'attendance.daily_timeline': 'Daily Timeline',
+  'auth.back_to_login': 'Back to Login',
+  'auth.cancel': 'Cancel',
+  'auth.forgot_check_inbox': 'Please check your inbox',
+  'auth.forgot_email_sent': 'Password reset email has been sent',
+  'auth.forgot_password_desc': 'Enter your email address to reset your password',
+  'auth.password_weak': 'Weak',
+  'auth.password_fair': 'Fair',
+  'auth.password_good': 'Good',
+  'auth.password_strong': 'Strong',
+  'auth.send_reset_link': 'Send Reset Link',
+  'competition.unlimited': 'Unlimited',
+  'date.jan': 'Jan',
+  'date.feb': 'Feb',
+  'date.mar': 'Mar',
+  'date.apr': 'Apr',
+  'date.may': 'May',
+  'date.jun': 'Jun',
+  'date.jul': 'Jul',
+  'date.aug': 'Aug',
+  'date.sep': 'Sep',
+  'date.oct': 'Oct',
+  'date.nov': 'Nov',
+  'date.dec': 'Dec',
+  'drawing.bg_type': 'Background Type',
+  'drawing.canvas_label': 'Canvas',
+  'label.selected': 'Selected',
+  'student_portal.daily_inspiration': 'Daily Inspiration',
   'polish.nav_setup': 'Setup',
   'polish.nav_teaching': 'Teaching',
   'polish.nav_analysis': 'Analysis',