Storage: share the card with a phone's browser (#88)

`w` in the Storage App starts a small HTTP server and shows its address,
as a QR code and in letters, with a six-digit code. A browser on the same
network that has typed the code can list, download, upload, make folders
and delete, under the Storage App's rules. The server runs only while that
screen is open. Nothing is encrypted, and the screen says so.

Uploads are streamed to the card under a temporary name and renamed when
whole. Every access to the card is handed to the storage task, 8 KB at a
time, from the server's own task.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/main.cpp

@@ -12,6 +12,7 @@
 #include "apps/demo_app.h"
 #include "apps/note_editor.h"
 #include "apps/shell_app.h"
+#include "services/web_share.h"
 #include "apps/gemini_app.h"
 #include "apps/gnss_app.h"
 #include "apps/irc_app.h"
@@ -216,7 +217,7 @@ void setup() {
     apps->registerApp({"gnss", "GNSS", false, new GnssApp(*gnssService, settings)});
     apps->registerApp({"gemini", "Gemini", false, new GeminiApp(*geminiService)});
     apps->registerApp({"lora", "LoRa Scanner", false, new LoraScannerApp(*radioService, *loraCapture, settings, *clockService)});
-    apps->registerApp({"storage", "Storage", false, new StorageApp(*fileOps, *storageService, *clockService, *update, *power, bus)});
+    apps->registerApp({"storage", "Storage", false, new StorageApp(*fileOps, *storageService, *clockService, *update, *power, bus, *new WebShare(*storageService, *fileOps, *wifi))});
     apps->registerApp({"notes", "Notes", false, new NotesApp(*fileOps, *storageService, *clockService, *power)});
     apps->registerApp({"shell", "Shell", false, new ShellApp(shellRun, shellProbe, shellList, shellCount, helpText(), *apps)});
     // Leaving the foreground App makes it save: a note being typed, when the device is powered off.