fix(auto-pause): never treat a failed clientlist as "channel empty"; default OFF

Auto-pause within the first seconds of playback (and re-pause after a manual
play) whenever a listener is actually in the channel.

Root cause (confirmed live against a TS3 server): the full-client
`clientlist -uid -away -voice -groups` command TIMES OUT when other clients are
present in the bot's channel. `getClientsInChannel()` catches the error and
returns `[]`, so the occupancy callers computed `userCount = [].length - 1 = -1`,
which `decideOccupancyAction` reads as `-1 <= 0` → "channel empty" → pause. With
the bot alone, clientlist succeeds (returns just the bot), so the bug only
surfaced when someone was listening — exactly the report.

Fix: a connected bot is always a member of its own channel, so a valid query
returns >= 1 (itself). A length of 0 therefore means the query FAILED, not that
the channel is empty. New pure helper `occupancyFromClientList()` maps a
0-length result to `null` ("occupancy unknown"); `refreshOccupancy()` and the
30s idle poller skip the auto-pause / idle-disconnect decision when the count is
unknown instead of mis-reading it as empty. This also removes a latent
false-positive idle-disconnect on the same failed query.

Also default `autoPauseOnEmpty` to OFF (occupancy detection is unreliable on
some servers); users can opt in from Settings.

Verified live with two clients in one channel: clientlist returns 0 → helper
returns null → no false pause (control: bot alone returns 1 → 0 others, normal).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/data/config.test.ts

@@ -49,7 +49,8 @@ describe("config", () => {
     // defaults should fill in the rest
     expect(loaded.theme).toBe("dark");
     expect(loaded.commandPrefix).toBe("!");
-    expect(loaded.autoPauseOnEmpty).toBe(true);
+    // auto-pause defaults OFF (occupancy detection is unreliable on some servers)
+    expect(loaded.autoPauseOnEmpty).toBe(false);
   });
 
   // --- #86: config.json must live under (and be created in) the persisted data dir ---

src/data/config.ts

@@ -36,7 +36,10 @@ export function getDefaultConfig(): BotConfig {
     adminPassword: "",
     adminGroups: [],
     autoReturnDelay: 300,
-    autoPauseOnEmpty: true,
+    // Default OFF: occupancy detection relies on the full-client `clientlist`
+    // command, which is unreliable on some servers (it can time out when other
+    // clients are present). Users can opt in from the web UI.
+    autoPauseOnEmpty: false,
     idleTimeoutMinutes: 0,
     publicUrl: "",
     trustProxy: false,