Telegram-Kanaele als Quelle: Parser, Pipeline, UI-Checkbox, Validate-Endpoint

- Neuer source_type telegram_channel in models.py (Source + Incident)
- DB-Migration: include_telegram Spalte fuer incidents
- feeds/telegram_parser.py: Telethon-basierter Parser (analog RSS)
- Orchestrator: Telegram-Pipeline parallel zu RSS + WebSearch
- sources.py: POST /api/sources/telegram/validate Endpoint
- incidents.py: include_telegram in Create/Update/Response
- dashboard.html: Telegram-Checkbox + Filter-Option
- app.js: FormData, EditModal, SourceStats, TypeLabels
- config.py: TELEGRAM_API_ID, API_HASH, SESSION_PATH
- requirements.txt: telethon hinzugefuegt

src/static/dashboard.html

@@ -339,6 +339,14 @@
                             </label>
                             <div class="form-hint" id="sources-hint">DE + internationale Feeds (Reuters, BBC, Al Jazeera etc.)</div>
                         </div>
+                        <div class="toggle-group" style="margin-top: 8px;">
+                            <label class="toggle-label">
+                                <input type="checkbox" id="inc-telegram">
+                                <span class="toggle-switch"></span>
+                                <span class="toggle-text">Telegram-Kanäle einbeziehen</span>
+                            </label>
+                            <div class="form-hint" id="telegram-hint">Nachrichten aus konfigurierten Telegram-Kanälen berücksichtigen</div>
+                        </div>
                     </div>
                     <div class="form-group">
                         <label>Sichtbarkeit</label>
@@ -427,6 +435,7 @@
                             <option value="">Alle Typen</option>
                             <option value="rss_feed">RSS-Feed</option>
                             <option value="web_source">Web-Quelle</option>
+                            <option value="telegram_channel">Telegram</option>
                             <option value="excluded">Von mir ausgeschlossen</option>
                         </select>
                         <label for="sources-filter-category" class="sr-only">Kategorie filtern</label>