Add public feed, admin area, self-registration, visibility & hashtags

- Public feed (/) with infinite scroll via Intersection Observer
- Self-registration (/register)
- Admin area (/admin/entries, /admin/users) with user management
- journal_entries: visibility (public/private) + hashtags fields
- users: is_admin flag
- DB schema updated (recreate DB to apply)
- CI: run go test via docker run (golang:1.25-alpine) — fixes 'go not found'

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

backend/internal/api/templates/day.html

@@ -13,6 +13,15 @@
         <label>Uhrzeit</label>
         <input type="time" name="time" required id="entry-time">
       </div>
+      <div class="form-col">
+        <label>Sichtbarkeit</label>
+        <select name="visibility">
+          <option value="private">Privat</option>
+          <option value="public">Öffentlich</option>
+        </select>
+      </div>
+    </div>
+    <div class="form-row">
       <div class="form-col">
         <label>GPS-Koordinaten <small>(optional)</small></label>
         <div class="gps-row">
@@ -22,6 +31,10 @@
         </div>
         <small id="gps-status"></small>
       </div>
+      <div class="form-col">
+        <label>Hashtags <small>(kommagetrennt, optional)</small></label>
+        <input type="text" name="hashtags" placeholder="reise, essen, natur">
+      </div>
     </div>
     <label>Überschrift</label>
     <input type="text" name="title" placeholder="Titel des Eintrags">
@@ -38,10 +51,12 @@
   <div class="entry-card">
     <div class="entry-meta">
       <strong>{{.EntryTime}}</strong>
+      {{if eq .Visibility "public"}}<span class="badge-public">öffentlich</span>{{end}}
       {{if .Lat}}<small> · &#9675; {{printf "%.5f" (deref .Lat)}}, {{printf "%.5f" (deref .Lon)}}</small>{{end}}
     </div>
     {{if .Title}}<div class="entry-title">{{.Title}}</div>{{end}}
     {{if .Description}}<div class="entry-desc">{{.Description}}</div>{{end}}
+    {{if .Hashtags}}<div class="hashtags">{{range .Hashtags}}<span class="tag">#{{.}}</span> {{end}}</div>{{end}}
     {{if .Images}}
     <div class="entry-images">
       {{range .Images}}
@@ -56,27 +71,8 @@
   <p><small>// Noch keine Einträge</small></p>
   {{end}}
 
-  <h2>Trackpunkte <small>({{len .Points}})</small></h2>
-  <figure>
-  <table>
-    <thead><tr><th>Zeit</th><th>Lat</th><th>Lon</th><th>Quelle</th><th>Notiz</th></tr></thead>
-    <tbody>
-    {{range .Points}}
-    <tr>
-      <td>{{.Timestamp.Format "15:04:05"}}</td>
-      <td>{{printf "%.5f" .Lat}}</td>
-      <td>{{printf "%.5f" .Lon}}</td>
-      <td class="source-{{.Source}}">{{.Source}}</td>
-      <td><small>{{.Note}}</small></td>
-    </tr>
-    {{else}}
-    <tr><td colspan="5"><small>// Keine Punkte</small></td></tr>
-    {{end}}
-    </tbody>
-  </table>
-  </figure>
-
   <h2>Aufenthalte <small>({{len .Stops}})</small></h2>
+  {{if .Stops}}
   <figure>
   <table>
     <thead><tr><th>Von</th><th>Bis</th><th>Dauer</th><th>Ort</th></tr></thead>
@@ -88,12 +84,34 @@
       <td><small>{{divInt .DurationS 60}} min</small></td>
       <td>{{if .PlaceLabel}}{{.PlaceLabel}}{{else}}<small>—</small>{{end}}</td>
     </tr>
-    {{else}}
-    <tr><td colspan="4"><small>// Keine Aufenthalte</small></td></tr>
     {{end}}
     </tbody>
   </table>
   </figure>
+  {{else}}
+  <p><small>// Keine Aufenthalte</small></p>
+  {{end}}
+
+  <details>
+    <summary><small>Trackpunkte ({{len .Points}})</small></summary>
+    <figure>
+    <table>
+      <thead><tr><th>Zeit</th><th>Lat</th><th>Lon</th><th>Quelle</th></tr></thead>
+      <tbody>
+      {{range .Points}}
+      <tr>
+        <td>{{.Timestamp.Format "15:04:05"}}</td>
+        <td>{{printf "%.5f" .Lat}}</td>
+        <td>{{printf "%.5f" .Lon}}</td>
+        <td class="source-{{.Source}}">{{.Source}}</td>
+      </tr>
+      {{else}}
+      <tr><td colspan="4"><small>// Keine Punkte</small></td></tr>
+      {{end}}
+      </tbody>
+    </table>
+    </figure>
+  </details>
 </main>
 {{end}}