fix: evaluation report P0/P1/P2 fixes, remove Docker, add upload UI

Backend:
- Add NotFoundException + BusinessException, return correct HTTP status (404/400)
- Add @Index on reports.project_id and reports.upload_time
- Add fileSize column to reports, populate on upload, return in DTO
- Cascade delete: deleting project now removes all reports (DB + files + PDFs)
- Delete report: also clean up pre-rendered PDF
- File upload MIME validation (extension + Content-Type)
- Remove duplicate @ExceptionHandler from ReportController
- Switch from System.err to SLF4J logger
- Handle MethodArgumentNotValid, MissingServletRequestPart, etc.

Frontend:
- Remove all Docker files (project uses 宝塔 panel deployment)
- Upgrade axios 1.6.8 -> 1.7.7 (CVE-2024-39338)
- Remove unused @vue-office/pptx + vue-demi (see CHANGELOG for rationale)
- Fix vite proxy port 37821 -> 30081
- Remove mock data fallback in production
- Add upload report UI (button + modal in ProjectDetail)
- Add create project UI (button + modal in ProjectList)
- Add filename search box in ProjectDetail
- New useApi methods: createProject, uploadReport, deleteProject, deleteReport
- FilePreview/ReportCard: show fileSize (was undefined before)

Docs:
- Add README.md (overview, quick start, structure)
- Add CHANGELOG.md (full change log + pptx removal rationale)
- Include EVALUATION_REPORT.md and blog-vibe-coding.md

Tests:
- All 73 backend tests pass
- All 43 frontend tests pass
- Updated test fixtures for new API contract

src/components/ReportCard.vue

@@ -41,7 +41,7 @@
               'text-sm',
               isSelected ? 'text-white/80' : 'text-slate-500'
             ]">
-              {{ report.size }}
+              {{ formatFileSize(report.fileSize) }}
             </span>
           </div>
         </div>
@@ -121,6 +121,13 @@ const formatDate = (isoString) => {
   return `${d.getFullYear()}-${pad(d.getMonth()+1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}`
 }
 
+const formatFileSize = (bytes) => {
+  if (bytes == null || isNaN(bytes)) return ''
+  if (bytes < 1024) return `${bytes} B`
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`
+  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`
+}
+
 const fileIconComponent = computed(() => FileIcon)
 
 const iconClass = computed(() => {