Fix timestamp timezone — logs now always show in IST regardless of server TZ

Root cause: postgres.js v3 parses `timestamp without timezone` columns as
`new Date("YYYY-MM-DD HH:mm:ss")` (space format, no Z). V8 treats this as
*local time*, so on a non-UTC server (Dokploy host = Europe/Helsinki UTC+3)
the parsed Date object is 3 hours off, making logged times show as server
time instead of the user's IST.

Fixes:
- db/index.ts: add custom `timestamp` type parser that forces UTC by
  converting space-format to ISO with 'Z' before calling new Date().
  Also set `connection: { TimeZone: "UTC" }` so PostgreSQL sessions always
  store/return timestamps in UTC regardless of server OS timezone.
- CalendarView.tsx: use `dateIST()` for day grouping (fixes midnight-boundary
  bug where a 12:30 AM IST entry appeared on the previous UTC day) and
  `fmtTime()` for time display (replaces toLocaleTimeString without timezone).
- MedicineTab.tsx: replace toLocaleString() with fmtDate/fmtTime (IST-aware).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/CalendarView.tsx

@@ -2,6 +2,7 @@
 
 import { useState, useMemo } from "react";
 import type { Log, LogType } from "@/types";
+import { dateIST, fmtTime } from "@/lib/date-ist";
 
 const TYPE_COLORS: Record<LogType, string> = {
   feed:   "bg-rose-400",
@@ -36,7 +37,7 @@ export function CalendarView({ logs, filter }: Props) {
   const logsByDate = useMemo(() => {
     const map: Record<string, Log[]> = {};
     filteredLogs.forEach(log => {
-      const key = new Date(log.loggedAt).toISOString().slice(0, 10);
+      const key = dateIST(log.loggedAt); // IST date, not UTC
       if (!map[key]) map[key] = [];
       map[key].push(log);
     });
@@ -173,7 +174,7 @@ export function CalendarView({ logs, filter }: Props) {
                     </div>
                   </div>
                   <div className="text-xs text-gray-400 flex-shrink-0">
-                    {new Date(log.loggedAt).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" })}
+                    {fmtTime(log.loggedAt)}
                   </div>
                 </div>
               ))}

src/components/medical/MedicineTab.tsx

@@ -4,6 +4,7 @@ import { useState, useEffect } from "react";
 import { Button, Input, Modal } from "@/components/ui";
 import { api } from "@/lib/api";
 import type { Medicine, Dose } from "@/types";
+import { fmtTime, fmtDate } from "@/lib/date-ist";
 
 interface Props { childId: string }
 
@@ -183,7 +184,7 @@ export function MedicineTab({ childId }: Props) {
                       <div className="flex justify-between items-start">
                         <div>
                           <span className="text-gray-600 dark:text-gray-300 font-medium">
-                            {new Date(d.administered_at).toLocaleString()}
+                            {fmtDate(d.administered_at, { month: "short", day: "numeric" })} {fmtTime(d.administered_at)}
                           </span>
                           {displayAmount && <span className="ml-2 text-gray-500">· {displayAmount}</span>}
                           {displayNotes  && <span className="ml-1 text-gray-400">· {displayNotes}</span>}
@@ -228,7 +229,7 @@ export function MedicineTab({ childId }: Props) {
           <p className="text-xs text-gray-400">Original is kept. A correction record is added.</p>
           {correctDose && (
             <div className="text-xs bg-gray-50 dark:bg-gray-700 rounded-lg p-2 text-gray-500 dark:text-gray-400">
-              Original: {correctDose.dose.amount_given || "—"} · {new Date(correctDose.dose.administered_at).toLocaleString()}
+              Original: {correctDose.dose.amount_given || "—"} · {fmtDate(correctDose.dose.administered_at, { month: "short", day: "numeric" })} {fmtTime(correctDose.dose.administered_at)}
             </div>
           )}
           <Input placeholder="Corrected amount" value={correctAmount} onChange={e => setCorrectAmount(e.target.value)} />

src/db/index.ts

@@ -8,7 +8,26 @@ const queryClient = postgres(connectionString, {
   max: 10,
   idle_timeout: 20,
   max_lifetime: 60 * 30,
-  // Prepare: true enables prepared statements
+  // Force the PostgreSQL session timezone to UTC so that `timestamp without
+  // time zone` columns are always stored and returned as UTC values,
+  // regardless of what timezone the host OS / Dokploy server is configured
+  // with (the Finnish server is UTC+3 in summer).
+  connection: { TimeZone: "UTC" },
+  // postgres.js v3 parses `timestamp` (OID 1114) with `new Date(rawString)`
+  // where rawString looks like "2024-05-28 09:00:00" (space, no Z).  V8
+  // treats that space-format string as *local* time, so on any server that
+  // isn't UTC the resulting Date object is wrong.  The fix: convert the
+  // space-format string to ISO 8601 with an explicit Z so V8 always
+  // interprets it as UTC, regardless of the Node.js process timezone.
+  types: {
+    timestamp: {
+      to: 1114,
+      from: [1114],
+      serialize: (x: Date | string) =>
+        (x instanceof Date ? x : new Date(x)).toISOString(),
+      parse: (x: string) => new Date(x.replace(" ", "T") + "Z"),
+    },
+  },
 });
 
 // Raw client for queries that need session context