fix: prefer wired modems in findModem() to prevent wireless/wired mismatch

WebBridge.findModem() iterated _G.device with pairs() which has
non-deterministic order. On computers with both wired and wireless
modems, it could return the wireless modem while the manager uses
a wired modem - messages never cross the wired/wireless boundary.

Now uses two-pass iteration: first looks for wired modems, then
falls back to any modem. Peripheral scan fallback also prefers wired.
Backward-compatible: boolean arg (preferWireless) still works.

apis/webbridge.lua

@@ -170,29 +170,57 @@ end
 
 --- Find a modem peripheral.
 -- Prefers the Opus device registry, falls back to peripheral scan.
--- @param preferWireless boolean|nil  If true, prefer wireless modem
+-- By default prefers wired modems (for reliable LAN communication).
+-- @param opts table|boolean|nil  Options table { preferWireless = bool },
+--   or legacy boolean (true = prefer wireless)
 -- @return table|nil  Modem peripheral handle
 -- @return string|nil  Peripheral name/side
-function WebBridge.findModem(preferWireless)
+function WebBridge.findModem(opts)
+  -- Legacy support: boolean arg means preferWireless
+  if type(opts) == 'boolean' then
+    opts = { preferWireless = opts }
+  end
+  opts = opts or {}
+
   -- Try Opus device registry first
   if _G.device then
-    if preferWireless and _G.device.wireless_modem then
+    if opts.preferWireless and _G.device.wireless_modem then
       return _G.device.wireless_modem, 'wireless_modem'
     end
-    -- Find any modem in device registry
+
+    -- Two-pass: prefer wired modems first, then any modem
+    -- (pairs() order is non-deterministic; without two passes,
+    --  a wireless modem might be returned even when wired is available)
+    local fallback, fallbackName
     for name, dev in pairs(_G.device) do
-      if dev.type == 'modem' or dev.type == 'wireless_modem' or dev.type == 'wired_modem' then
+      if dev.type == 'wired_modem' then
         return dev, name
+      elseif dev.type == 'modem' or dev.type == 'wireless_modem' then
+        if not fallback then
+          fallback, fallbackName = dev, name
+        end
       end
     end
+    if fallback then
+      return fallback, fallbackName
+    end
   end
 
-  -- Fallback: scan peripherals
+  -- Fallback: scan peripherals (prefer wired)
+  local wirelessDev, wirelessName
   for _, name in ipairs(peripheral.getNames()) do
     if peripheral.getType(name) == 'modem' then
-      return peripheral.wrap(name), name
+      local dev = peripheral.wrap(name)
+      if dev.isWireless and not dev.isWireless() then
+        return dev, name  -- wired modem found
+      elseif not wirelessDev then
+        wirelessDev, wirelessName = dev, name
+      end
     end
   end
+  if wirelessDev then
+    return wirelessDev, wirelessName
+  end
 
   return nil
 end