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/static/css/style.css

@@ -325,7 +325,10 @@ p {
 /* 입력 */
 input[type="text"],
 input[type="time"],
-input[type="password"] {
+input[type="date"],
+input[type="password"],
+select,
+textarea {
   width: 100%;
   font-family: inherit;
   font-size: 15px;
@@ -336,6 +339,33 @@ input[type="password"] {
   color: var(--color-text);
 }
 
+textarea {
+  resize: vertical;
+  min-height: 90px;
+  line-height: 1.5;
+}
+
+select {
+  cursor: pointer;
+}
+
+input[type="file"] {
+  width: 100%;
+  font-family: inherit;
+  font-size: 14px;
+  color: var(--color-text-muted);
+}
+
+input[type="color"] {
+  width: 56px;
+  height: 40px;
+  padding: 2px;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-control);
+  background: var(--color-bg);
+  cursor: pointer;
+}
+
 label {
   display: block;
   font-size: 13px;
@@ -466,6 +496,32 @@ label {
   color: #fff;
 }
 
+/* 저널 기분 선택 pill */
+.mood-picker {
+  display: flex;
+  gap: 6px;
+  flex-wrap: wrap;
+}
+
+.mood-pill {
+  border-radius: 999px;
+  border: 1px solid var(--color-border);
+  background: transparent;
+  color: var(--color-text-muted);
+  font-size: 14px;
+  padding: 8px 12px;
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+}
+
+.mood-pill.selected {
+  background: var(--color-accent);
+  border-color: var(--color-accent);
+  color: #fff;
+}
+
 .difficulty-hint {
   font-size: 12px;
   color: var(--color-text-muted);
@@ -810,6 +866,115 @@ label {
   color: var(--color-border);
 }
 
+/* 저널링 */
+.journal-day-dots {
+  display: flex;
+  gap: 2px;
+}
+
+.journal-day-dot {
+  width: 5px;
+  height: 5px;
+  border-radius: 50%;
+}
+
+.journal-prompt-card,
+.on-this-day-card {
+  margin-top: var(--space-2);
+  padding: var(--space-2);
+  border-radius: var(--radius-control);
+  background: var(--color-success-tint);
+  font-size: 14px;
+}
+
+.journal-entry-item {
+  padding: 10px 0;
+  border-bottom: 1px solid var(--color-border);
+}
+
+.journal-entry-item:last-child {
+  border-bottom: none;
+}
+
+.journal-entry-title {
+  font-weight: 600;
+  margin-top: 6px;
+}
+
+.journal-entry-content {
+  white-space: pre-wrap;
+  margin-top: 4px;
+}
+
+.journal-entry-tags {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 6px;
+  margin-top: 8px;
+}
+
+.tag-chip {
+  font-size: 12px;
+  color: var(--color-text-muted);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: 999px;
+  padding: 2px 8px;
+}
+
+.mood-icon {
+  font-size: 18px;
+}
+
+.attachment-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
+  gap: 8px;
+  margin-top: 8px;
+}
+
+.attachment-thumb {
+  position: relative;
+  aspect-ratio: 1;
+  border-radius: var(--radius-control);
+  overflow: hidden;
+  border: 1px solid var(--color-border);
+}
+
+.attachment-thumb img {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  display: block;
+}
+
+.attachment-video-link {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 100%;
+  font-size: 12px;
+  text-align: center;
+  color: var(--color-text-muted);
+  text-decoration: none;
+  padding: 4px;
+}
+
+.attachment-delete-btn {
+  position: absolute;
+  top: 2px;
+  right: 2px;
+  width: 20px;
+  height: 20px;
+  border-radius: 50%;
+  border: none;
+  background: rgba(0, 0, 0, 0.6);
+  color: #fff;
+  font-size: 14px;
+  line-height: 1;
+  cursor: pointer;
+}
+
 /* 랜딩 페이지 (/) */
 .landing {
   max-width: 480px;