feat(sessions): add channelIdleMinutes config for per-channel session idle durations (#1353)

* feat(sessions): add channelIdleMinutes config for per-channel session idle durations

Add new `channelIdleMinutes` config option to allow different session idle
timeouts per channel. For example, Discord sessions can now be configured
to last 7 days (10080 minutes) while other channels use shorter defaults.

Config example:
  sessions:
    channelIdleMinutes:
      discord: 10080  # 7 days

The channel-specific idle is passed as idleMinutesOverride to the existing
resolveSessionResetPolicy, integrating cleanly with the new reset policy
architecture.

* fix

* feat: add per-channel session reset overrides (#1353) (thanks @cash-echo-bot)

---------

Co-authored-by: Cash Williams <cashwilliams@gmail.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/web/auto-reply/session-snapshot.test.ts

@@ -8,7 +8,7 @@ import { saveSessionStore } from "../../config/sessions.js";
 import { getSessionSnapshot } from "./session-snapshot.js";
 
 describe("getSessionSnapshot", () => {
-  it("uses heartbeat idle override while daily reset still applies", async () => {
+  it("uses channel reset overrides when configured", async () => {
     vi.useFakeTimers();
     vi.setSystemTime(new Date(2026, 0, 18, 5, 0, 0));
     try {
@@ -20,6 +20,7 @@ describe("getSessionSnapshot", () => {
         [sessionKey]: {
           sessionId: "snapshot-session",
           updatedAt: new Date(2026, 0, 18, 3, 30, 0).getTime(),
+          lastChannel: "whatsapp",
         },
       });
 
@@ -27,7 +28,9 @@ describe("getSessionSnapshot", () => {
         session: {
           store: storePath,
           reset: { mode: "daily", atHour: 4, idleMinutes: 240 },
-          heartbeatIdleMinutes: 30,
+          resetByChannel: {
+            whatsapp: { mode: "idle", idleMinutes: 360 },
+          },
         },
       } as Parameters<typeof getSessionSnapshot>[0];
 
@@ -35,9 +38,10 @@ describe("getSessionSnapshot", () => {
         sessionKey,
       });
 
-      expect(snapshot.resetPolicy.idleMinutes).toBe(30);
-      expect(snapshot.fresh).toBe(false);
-      expect(snapshot.dailyResetAt).toBe(new Date(2026, 0, 18, 4, 0, 0).getTime());
+      expect(snapshot.resetPolicy.mode).toBe("idle");
+      expect(snapshot.resetPolicy.idleMinutes).toBe(360);
+      expect(snapshot.fresh).toBe(true);
+      expect(snapshot.dailyResetAt).toBeUndefined();
     } finally {
       vi.useRealTimers();
     }