httpd: raise the default web session timeout to one hour

200 seconds was too short in practice: the UI stops polling while its
tab is hidden, so looking at another tab for a few minutes ended the
session. Make it 3600 seconds; "session <seconds>" still overrides it.

CHANGELOG.md

@@ -23,6 +23,11 @@
 
 ## Changed
 
+- Web UI
+  - The web session expires after one hour without a request (was 200 seconds). The UI stops
+    polling while its tab is hidden, so with 200 seconds switching tabs for a few minutes logged
+    you out. `session <seconds>` still sets it.
+
 ## Fixed
 
 - Time

README.md

@@ -356,7 +356,7 @@ netmask zzz.zzz.zzz.zzz = Network mask of the switch
 port x name xxx         = Name xxx the port number x
 port z 1g               = Set 1g speed for port z
 igmp on/off             = Turn IGMP on or off
-session xxxx            = Web session timeout in seconds (default 200)
+session xxxx            = Web session timeout in seconds (default 3600)
 ```
 [To be continue]
 

httpd/httpd.c

@@ -12,7 +12,7 @@
 // #define DEBUG
 #include "debug.h"
 
-#define SESSION_TIMEOUT_DEFAULT 200
+#define SESSION_TIMEOUT_DEFAULT 3600
 
 /* Seconds of inactivity after which a session cookie stops validating.
  * Configurable with the "session" command, see cmd_parser.c. */