Setup-Seite: Kanal-Auswahl, Feed-Regeln und Status im Webinterface

- Settings-Tabelle in SQLite; Env-Variablen nur noch Fallback, Änderungen greifen sofort
- /settings (Admin): Devlog-/Commit-Kanal als Dropdown aus allen sichtbaren Textkanälen,
  je mit Test-senden-Button
- Commit-Feed-Regeln: an/aus, Branch-Filter, ignorierte Repos (archiviert wird immer,
  gefiltert wird nur das Posten; ignorierte Repos komplett übersprungen)
- Status-Panel: Bot-Tag, Uptime, Devlog-/Commit-Zahlen, DB-Größe
- API: GET/PUT /api/settings, POST /api/settings/test/:target (alles Admin-only)
- COMMIT_CHANNEL_ID/DEVLOG_CHANNEL_ID in config optional

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/db.js

@@ -1,6 +1,6 @@
 // SQLite-Anbindung (better-sqlite3, synchron & schnell) — Schema wird beim Start angelegt
 import Database from 'better-sqlite3';
-import { mkdirSync } from 'node:fs';
+import { mkdirSync, statSync } from 'node:fs';
 import { dirname, resolve } from 'node:path';
 import { config } from './config.js';
 
@@ -41,6 +41,22 @@ if (!devlogCols.some((c) => c.name === 'images')) {
     db.exec(`ALTER TABLE devlogs ADD COLUMN images TEXT NOT NULL DEFAULT '[]'`);
 }
 
+// Laufzeit-Einstellungen (Settings-Seite im Webinterface) — überschreiben Env-Defaults
+db.exec('CREATE TABLE IF NOT EXISTS settings (key TEXT PRIMARY KEY, value TEXT NOT NULL)');
+const getSettingStmt = db.prepare('SELECT value FROM settings WHERE key = ?');
+const setSettingStmt = db.prepare(`
+    INSERT INTO settings (key, value) VALUES (?, ?)
+    ON CONFLICT(key) DO UPDATE SET value = excluded.value
+`);
+
+export function getSetting(key) {
+    return getSettingStmt.get(key)?.value ?? null;
+}
+
+export function setSetting(key, value) {
+    setSettingStmt.run(key, value);
+}
+
 const insertCommit = db.prepare(`
     INSERT OR IGNORE INTO commits (sha, repo, branch, message, author_name, author_user, url, committed_at)
     VALUES (@sha, @repo, @branch, @message, @author_name, @author_user, @url, @committed_at)
@@ -103,3 +119,12 @@ const countCommitsStmt = db.prepare('SELECT COUNT(*) AS n FROM commits');
 export function listCommits(limit, offset) {
     return { items: selectCommits.all(limit, offset), total: countCommitsStmt.get().n };
 }
+
+/** Statistiken fürs Status-Panel der Settings-Seite */
+export function archiveStats() {
+    return {
+        devlogs: countDevlogsStmt.get().n,
+        commits: countCommitsStmt.get().n,
+        dbSizeBytes: statSync(dbFile).size,
+    };
+}