add journaling feature: categories, tags, attachments, calendar, and multi-select emotions

Adds an 8th development stage that lets users keep a free-form journal alongside
habit tracking, reusing the existing Google OAuth/DB/PWA infrastructure instead
of a separate project. Users organize entries into custom categories, filter by
a month calendar with day-detail drill-down, attach photos/videos (served via an
authenticated route, never /static), tag entries, and pick multiple emotions per
entry from a curated 9-option set. Includes a global journal prompt bank for
lightweight guided journaling.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/models/__init__.py

@@ -1,5 +1,15 @@
 from app.models.habit import Habit, HabitStatus, HabitType
 from app.models.habit_log import HabitLog
+from app.models.journal import (
+    JournalAttachment,
+    JournalAttachmentType,
+    JournalCategory,
+    JournalEntry,
+    JournalEntryMood,
+    JournalMood,
+    JournalPrompt,
+    JournalTag,
+)
 from app.models.notification_log import HabitNotificationLog, SummaryNotificationLog
 from app.models.push_subscription import PushSubscription
 from app.models.user import User
@@ -9,6 +19,14 @@ __all__ = [
     "HabitStatus",
     "HabitType",
     "HabitLog",
+    "JournalAttachment",
+    "JournalAttachmentType",
+    "JournalCategory",
+    "JournalEntry",
+    "JournalEntryMood",
+    "JournalMood",
+    "JournalPrompt",
+    "JournalTag",
     "HabitNotificationLog",
     "SummaryNotificationLog",
     "PushSubscription",