Add background filtering jobs, improved date picker, AI reasoning display

- Implement background job system for AI filtering to avoid HTTP timeouts
- Add FilteringJob model to track progress of long-running filtering operations
- Add real-time progress polling for filtering operations on round details page
- Create custom DateTimePicker component with calendar popup (no year picker hassle)
- Fix round date persistence bug (refetchOnWindowFocus was resetting form state)
- Integrate filtering controls into round details page for filtering rounds
- Display AI reasoning for flagged/filtered projects in results table
- Add onboarding system scaffolding (schema, routes, basic UI)
- Allow setting round dates in the past for manual overrides

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package-lock.json

@@ -61,6 +61,7 @@
         "openai": "^6.16.0",
         "papaparse": "^5.4.1",
         "react": "^19.0.0",
+        "react-day-picker": "^9.13.0",
         "react-dom": "^19.0.0",
         "react-easy-crop": "^5.5.6",
         "react-hook-form": "^7.54.2",
@@ -268,6 +269,12 @@
       "integrity": "sha512-5dyB8nLC/qogMrlCizZnYWQTA4lnb/v+It+sqNl5YnSRAPMlIqY/X0Xn+gZw8vOL+TgTTr28VEbn3uf8fUtAkw==",
       "license": "MIT"
     },
+    "node_modules/@date-fns/tz": {
+      "version": "1.4.1",
+      "resolved": "https://registry.npmjs.org/@date-fns/tz/-/tz-1.4.1.tgz",
+      "integrity": "sha512-P5LUNhtbj6YfI3iJjw5EL9eUAG6OitD0W3fWQcpQjDRc/QIsL0tRNuO1PcDvPccWL1fSTXXdE1ds+l95DV/OFA==",
+      "license": "MIT"
+    },
     "node_modules/@dnd-kit/accessibility": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/@dnd-kit/accessibility/-/accessibility-3.1.1.tgz",
@@ -6343,6 +6350,12 @@
         "url": "https://github.com/sponsors/kossnocorp"
       }
     },
+    "node_modules/date-fns-jalali": {
+      "version": "4.1.0-0",
+      "resolved": "https://registry.npmjs.org/date-fns-jalali/-/date-fns-jalali-4.1.0-0.tgz",
+      "integrity": "sha512-hTIP/z+t+qKwBDcmmsnmjWTduxCg+5KfdqWQvb2X/8C9+knYY6epN/pfxdDuyVlSVeFz0sM5eEfwIUQ70U4ckg==",
+      "license": "MIT"
+    },
     "node_modules/dayjs": {
       "version": "1.11.19",
       "resolved": "https://registry.npmjs.org/dayjs/-/dayjs-1.11.19.tgz",
@@ -11638,6 +11651,27 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/react-day-picker": {
+      "version": "9.13.0",
+      "resolved": "https://registry.npmjs.org/react-day-picker/-/react-day-picker-9.13.0.tgz",
+      "integrity": "sha512-euzj5Hlq+lOHqI53NiuNhCP8HWgsPf/bBAVijR50hNaY1XwjKjShAnIe8jm8RD2W9IJUvihDIZ+KrmqfFzNhFQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@date-fns/tz": "^1.4.1",
+        "date-fns": "^4.1.0",
+        "date-fns-jalali": "^4.1.0-0"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "funding": {
+        "type": "individual",
+        "url": "https://github.com/sponsors/gpbl"
+      },
+      "peerDependencies": {
+        "react": ">=16.8.0"
+      }
+    },
     "node_modules/react-dom": {
       "version": "19.2.4",
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-19.2.4.tgz",