Updates: a download that breaks is carried on

When the connection breaks during a release download (issue #54), the
device waits up to a minute for Wi-Fi, asks for the rest of the file
with a Range request and carries on: the slot and the hash so far are
kept. It gives up after three tries in a row that bring nothing.
Nothing is kept across a restart.

Carrying on asks for 64 KB free, not 80: between two connections of an
install 78 KB is free, and the first attempt on the device was refused
for that. update damage cut now breaks every connection after n bytes.

Tried on the device: v0.23.0 installed over four connections, and a
download that brought nothing given up with nothing switched.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

src/main.cpp

@@ -579,6 +579,7 @@ static void updateCommand(const String& args) {
         console.printf("update: installing by itself %s%s%s\n", settings.getBool(Setting::InstallUpdates) ? "on" : "off",
                        autoUpdate.waiting() ? ", waiting for a quiet moment to offer " : autoUpdate.asking() ? ", asking about " : "",
                        autoUpdate.waiting() || autoUpdate.asking() ? autoUpdate.tag().c_str() : "");
+        console.printf("update: the last download was carried on %d time(s) after a break\n", update->lastResumes());
         console.printf("update: gitea %s %s\n", g.status() == GiteaReleases::Status::Done ? "done" : g.status() == GiteaReleases::Status::Failed ? "failed" : g.status() == GiteaReleases::Status::Busy ? "busy" : "never asked", g.error().c_str());
         printReleases(false);
     } else if (args.startsWith("install ")) {
@@ -594,7 +595,8 @@ static void updateCommand(const String& args) {
     } else if (args.startsWith("damage ")) {  // update damage cut <bytes> | flip <offset>: for the next download
         long n = args.substring(args.lastIndexOf(' ') + 1).toInt();
         args.startsWith("damage cut") ? update->damageNextDownload(n, -1) : update->damageNextDownload(-1, n);
-        console.printf("update: the next download will be %s at byte %ld\n", args.startsWith("damage cut") ? "cut" : "damaged", n);
+        if (args.startsWith("damage cut")) console.printf("update: each connection of the next download will break after %ld bytes\n", n);
+        else console.printf("update: the next download will be damaged at byte %ld\n", n);
 
     } else if (args == "daily") {  // forget today's check: the daily one runs again at once, if it may
         update->forgetToday();