GPT : Timezone and reporting improvements

Add timezone-aware timestamp support and reporting improvements
Store timestamps in ISO-8601 format with timezone offsets
Accept client-local timestamps from browser and API
Normalize legacy naive timestamps during parsing
Add migration script for converting old SQLite timestamps
Fix mixed naive/aware datetime comparison errors
Render timestamps in browser-local timezone
Auto-generate default 7-day reports on page load
Expand default dashboard report to include all users
Preserve manual single-user report generation
Add curl-based validation/test script for API and report flows

test.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+
+set -e
+
+BASE_URL="http://127.0.0.1:5000"
+
+echo "======================================="
+echo "Fetching users"
+echo "======================================="
+
+curl -s \
+    "${BASE_URL}/api/users" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Clocking IN user 1"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -H "Content-Type: application/json" \
+    -d '{
+        "user_id": 1,
+        "entrytype": "in",
+        "timestamp": "2026-05-29T08:00:00-04:00"
+    }' \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+sleep 1
+
+echo
+echo "======================================="
+echo "Clocking OUT user 1"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -H "Content-Type: application/json" \
+    -d '{
+        "user_id": 1,
+        "entrytype": "out",
+        "timestamp": "2026-05-29T17:00:00-04:00"
+    }' \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Fetching entries"
+echo "======================================="
+
+curl -s \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Generating report through web form"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -d "user_id=1" \
+    -d "action=report" \
+    -d "begin_date=2026-05-22T00:00:00-04:00" \
+    -d "end_date=2026-05-29T23:59:59-04:00" \
+    "${BASE_URL}/" \
+    > report.html
+
+echo "Report saved to report.html"
+
+echo
+echo "======================================="
+echo "Done"
+echo "======================================="