INBOX-0: Gmail request inbox backend (MailKit) + Request entity + sync/triage endpoints

- Request entity (GmailMessageId unique, ThreadId, threading headers, From*, Subject, BodyText,
  ReceivedAt, Status enum-as-string New|InProgress|Assigned|Answered|Abandoned, AssignedContactId? FK,
  DraftReply?, AnsweredAt?). MailSettings singleton (GmailAddress, AppPassword ENCRYPTED via Data
  Protection, PollInterval, Folder, LastUid). Migration AddRequestsAndMailSettings.
- IGmailMailReader (mockable) + MailKit GmailMailReader (imap.gmail.com:993 SSL, envelope+X-GM-THRID
  +body). RequestSyncService: dedup on Message-Id, track LastUid. MailKit 4.17.0.
- Endpoints: POST /api/requests/sync, GET /api/requests (Gridify, filter status), GET /api/requests/{id},
  PUT triage (status+assignedContactId), GET/PUT /api/mail-settings (App Password never returned).
- Tests (in-memory DB + canned reader): sync dedup/idempotency/config-guard, HTTP sync->triage->assign,
  mail-settings secrecy. + gitignore the runtime photo-storage/ dir (god housekeeping).

GerbilManagerWebAPI/Inbox/RequestSyncService.cs

@@ -0,0 +1,69 @@
+using GerbilManagerWebAPI.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace GerbilManagerWebAPI.Inbox
+{
+    /// <summary>
+    /// Imports Gmail messages into Request rows: dedup on Message-Id, track the highest IMAP
+    /// UID to avoid rescans. The actual fetch is behind <see cref="IGmailMailReader"/> (mockable).
+    /// </summary>
+    public sealed class RequestSyncService
+    {
+        private readonly ApplicationContext _db;
+        private readonly IGmailMailReader _reader;
+        private readonly MailSettingsService _settings;
+
+        public RequestSyncService(ApplicationContext db, IGmailMailReader reader, MailSettingsService settings)
+        {
+            _db = db;
+            _reader = reader;
+            _settings = settings;
+        }
+
+        public async Task<SyncResult> SyncAsync(CancellationToken ct = default)
+        {
+            var settings = await _settings.GetAsync(ct);
+            var password = _settings.DecryptPassword(settings);
+            if (string.IsNullOrWhiteSpace(settings.GmailAddress) || string.IsNullOrWhiteSpace(password))
+                return new SyncResult(0, "MailNotConfigured");
+
+            var conn = new MailConnection(settings.GmailAddress!, password!, settings.Folder);
+            var summaries = await _reader.FetchAsync(conn, settings.LastUid, ct);
+
+            uint maxUid = settings.LastUid;
+            int imported = 0;
+            if (summaries.Count > 0)
+            {
+                var fetchedIds = summaries.Select(s => s.MessageId).Where(id => !string.IsNullOrEmpty(id)).ToList();
+                var existing = (await _db.Requests
+                    .Where(r => fetchedIds.Contains(r.GmailMessageId))
+                    .Select(r => r.GmailMessageId).ToListAsync(ct)).ToHashSet();
+
+                foreach (var m in summaries)
+                {
+                    if (m.Uid > maxUid) maxUid = m.Uid;
+                    if (string.IsNullOrEmpty(m.MessageId) || !existing.Add(m.MessageId)) continue;
+                    _db.Requests.Add(new Request
+                    {
+                        Id = Guid.NewGuid(),
+                        GmailMessageId = m.MessageId,
+                        ThreadId = m.ThreadId,
+                        InReplyToMessageId = m.InReplyTo,
+                        ReferencesHeader = m.References,
+                        FromAddress = m.FromAddress,
+                        FromName = m.FromName,
+                        Subject = m.Subject,
+                        BodyText = m.BodyText,
+                        ReceivedAt = m.ReceivedAt,
+                        Status = RequestStatus.New,
+                    });
+                    imported++;
+                }
+            }
+
+            settings.LastUid = maxUid;
+            await _db.SaveChangesAsync(ct);
+            return new SyncResult(imported, null);
+        }
+    }
+}