feat: per-profile separate SQLite logbook file (config never swapped)

Design flaw: the SQLite backend conflated the app/config database (opslog.db —
settings + profiles) with the QSO logbook. connectLogbook returned a.db for any
non-MySQL profile, so the ONLY way to get a separate SQLite logbook was the
whole-app "change database location" pointer — which swapped config + profiles
too, wiping the operator's setup (reported: creating Jerem.db lost all configs).

profile.ProfileDB gains a Path field: a non-empty path routes that profile's
logbook to its own SQLite file (db.Open creates + migrates it on first use),
while opslog.db keeps settings/profiles. connectLogbook opens the file; empty
path = shared db (unchanged default, backward compatible). MySQLSettings carries
sqlite_path; Get/Save wire it through.

UI: the Database panel gains a third backend option "SQLite — separate file"
with a file picker, and now clearly labels the shared application database
(settings + profiles) vs this profile's logbook, so the two are never confused.

frontend/src/components/SettingsModal.tsx

@@ -1299,7 +1299,7 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
 
   const [dbSettings, setDbSettings] = useState<{ path: string; default_path: string; is_custom: boolean }>({ path: '', default_path: '', is_custom: false });
   const [dbMsg, setDbMsg] = useState('');
-  type MySQLCfg = { enabled: boolean; host: string; port: number; user: string; password: string; database: string };
+  type MySQLCfg = { enabled: boolean; host: string; port: number; user: string; password: string; database: string; sqlite_path?: string };
   const [mysqlCfg, setMysqlCfg] = useState<MySQLCfg>({ enabled: false, host: '', port: 3306, user: '', password: '', database: '' });
   const setMysqlField = (patch: Partial<MySQLCfg>) => setMysqlCfg((s) => ({ ...s, ...patch }));
   const [mysqlMsg, setMysqlMsg] = useState('');
@@ -4310,10 +4310,22 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
     // Switching the logbook backend applies immediately (no restart): the local
     // SQLite file always stays the config store; only the QSO logbook moves.
     function useLocalLogbook() {
-      SaveMySQLSettings({ ...mysqlCfg, enabled: false } as any)
-        .then(async () => { setMysqlField({ enabled: false }); setRestartMsg(t('db.switchedSqlite')); await refreshBackend(); })
+      SaveMySQLSettings({ ...mysqlCfg, enabled: false, sqlite_path: '' } as any)
+        .then(async () => { setMysqlField({ enabled: false, sqlite_path: '' }); setRestartMsg(t('db.switchedSqlite')); await refreshBackend(); })
         .catch((e: any) => setErr(String(e?.message ?? e)));
     }
+    // Route THIS profile's logbook to its own SQLite file (config stays in
+    // opslog.db). db.Open creates+migrates the file if it's new. Pick a name/place.
+    async function pickSeparateSqlite() {
+      try {
+        const p = await PickSaveDatabase();
+        if (!p) return;
+        await SaveMySQLSettings({ ...mysqlCfg, enabled: false, sqlite_path: p } as any);
+        setMysqlField({ enabled: false, sqlite_path: p });
+        setRestartMsg(t('db.switchedSqliteFile'));
+        await refreshBackend();
+      } catch (e: any) { setErr(String(e?.message ?? e)); }
+    }
     function connectMysql() {
       SaveMySQLSettings(mysqlCfg as any)
         .then(async () => { setRestartMsg(t('db.switchedMysql')); await refreshBackend(); })
@@ -4329,17 +4341,20 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
         <div className="grid grid-cols-[130px_1fr] gap-2 items-center max-w-2xl mb-1">
           <Label className="text-sm">{t('db.backend')}</Label>
           <Select
-            value={mysqlCfg.enabled ? 'mysql' : 'sqlite'}
+            value={mysqlCfg.enabled ? 'mysql' : (mysqlCfg.sqlite_path ? 'sqlite_file' : 'sqlite')}
             onValueChange={(v) => {
-              const enabled = v === 'mysql';
-              setMysqlField({ enabled });
               setRestartMsg('');
-              if (!enabled) useLocalLogbook();   // switching to local applies at once
+              if (v === 'mysql') { setMysqlField({ enabled: true }); return; }
+              if (v === 'sqlite') { useLocalLogbook(); return; }      // shared app db
+              // sqlite_file: keep any existing path; if none, prompt to pick one.
+              setMysqlField({ enabled: false });
+              if (!mysqlCfg.sqlite_path) pickSeparateSqlite();
             }}
           >
             <SelectTrigger className="h-8 w-72"><SelectValue /></SelectTrigger>
             <SelectContent>
               <SelectItem value="sqlite">{t('db.optSqlite')}</SelectItem>
+              <SelectItem value="sqlite_file">{t('db.optSqliteFile')}</SelectItem>
               <SelectItem value="mysql">{t('db.optMysql')}</SelectItem>
             </SelectContent>
           </Select>
@@ -4362,10 +4377,27 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
         )}
 
         {/* SQLite: local logbook file management */}
-        {!mysqlCfg.enabled && (
+        {/* Separate per-profile SQLite logbook FILE (config stays in opslog.db) */}
+        {!mysqlCfg.enabled && mysqlCfg.sqlite_path && (
+        <div className="space-y-3 max-w-2xl">
+          <div className="space-y-1">
+            <Label>{t('db.logbookFile')}</Label>
+            <div className="font-mono text-xs bg-muted/40 border border-border rounded-md px-3 py-2 break-all">{mysqlCfg.sqlite_path}</div>
+            <p className="text-[11px] text-muted-foreground">{t('db.logbookFileHint')}</p>
+          </div>
+          <div className="flex flex-wrap gap-2">
+            <Button variant="outline" size="sm" onClick={pickSeparateSqlite}><FolderOpen className="size-3.5" /> {t('db.chooseFile')}</Button>
+          </div>
+          {restartMsg && <div className="text-xs text-success-muted-foreground">{restartMsg}</div>}
+        </div>
+        )}
+
+        {/* Shared application/config database (opslog.db) = settings + profiles +
+            this profile's QSOs when it uses the default logbook. */}
+        {!mysqlCfg.enabled && !mysqlCfg.sqlite_path && (
         <div className="space-y-4 max-w-2xl">
           <div className="space-y-1">
-            <Label>{t('db.current')}</Label>
+            <Label>{t('db.appDb')}</Label>
             <div className="font-mono text-xs bg-muted/40 border border-border rounded-md px-3 py-2 break-all">
               {dbSettings.path || '—'}
               {dbSettings.is_custom
@@ -4373,6 +4405,7 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
                 : <span className="ml-2 text-[10px] text-muted-foreground">{t('db.default')}</span>}
             </div>
             <div className="text-[10px] text-muted-foreground">{t('db.defaultLabel')} <span className="font-mono">{dbSettings.default_path}</span></div>
+            <p className="text-[11px] text-muted-foreground">{t('db.appDbHint')}</p>
           </div>
 
           <div className="flex flex-wrap gap-2">