Virtualization phase 2: ISOs, New VM from ISO, the VGA console in the browser, nightly exports, mounts, instance sensors

- Library: an ISO shelf in virt/isos: upload (the Files uploader), fetch by URL with an
  optional sha256, import a file from the machine by copying it in, rename, delete (refused
  while attached), attach to a VM as a CD-ROM live or stopped with boot-first, eject, and
  New VM from ISO: an empty VM with the ISO as first boot device, Secure Boot on or off.
- The VGA console: Ham Lab asks Incus for the VM's SPICE console over its unix socket and
  bridges the display websocket to the browser, where spice-html5 (vendored from upstream
  b372aab, LGPL, loaded on demand) draws it; Ctrl+Alt+Del, fit-to-window.
- Exports: every instance as a tarball in virt/exports/<name>/, kept to a count, as a cron
  line in /etc/cron.d/hamlab-virt calling hamlab virt-export, settings and the last run
  as files beside the data; Export now per instance or for all.
- Disks tab per instance: the root disk, attached ISOs with Eject, bind mounts in and out
  (shift for containers, virtiofs for VMs).
- instance.* sensors (running, down, state, cpu, mem) and the VM-or-container-down alert
  default, offered once to installs seeded before it existed.
- cloud-init: Use my SSH keys writes a cloud-config from the account's public keys.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

web/src/vendor/spice-html5/spice.css

@@ -0,0 +1,168 @@
+body
+{
+    background-color: #999999;
+    color: #000000; 
+    margin: 0;
+    padding: 0;
+    font-family: "Lucida Grande", "Lucida Sans Unicode", "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;
+    font-size: 12pt;
+    line-height: 1.5em;
+}
+
+* { margin: 0; }
+
+button
+{
+    cursor: pointer;
+    color: #000000;
+    background-color: #999999;
+    border: 1px solid #4a4a4a;
+    min-width: 150px;
+    border-radius: 10px;
+    background: -webkit-gradient(linear, left top, left bottom, from(#fff), to(#24414e));
+    background: -moz-linear-gradient(top, #fff, #24414e);
+    -ms-transform: translate(15%, -8%);
+    transform: translate(15%, -8%);
+    font-size: .90em;
+    font-weight: bolder;
+    padding: 0px 0px 3px 0px;
+    margin-top: 5px;
+}
+button:focus
+{
+    outline: none;
+}
+button:hover
+{
+    background-color: #24414e
+}
+button:active
+{
+    background-color: #24414e;
+    transform: translate(14.85%, -7%);
+}
+
+.SidenavClosed
+{
+    height: 100%;
+    width: 0;
+    position: fixed;
+    z-index: 1;
+    top: 0;
+    left: 0;
+    background-color: #bbbbbb;
+    box-shadow: 1px 0px #00000040;
+    overflow-x: hidden;
+    transition: 0.5s;
+    padding-top: 60px;
+}
+.SidenavOpen
+{
+    height: 100%;
+    width: 200px !important;
+    position: fixed;
+    z-index: 1;
+    top: 0;
+    left: 0;
+    background-color: #bbbbbb;
+    box-shadow: 1px 0px #00000040;
+    overflow-x: hidden;
+    transition: 0.5s;
+    padding-top: 60px;
+}
+#Sidenav label
+{ 
+    color: #000000;
+    margin-left: 3%;
+    text-shadow: 1px 1px 0px rgba(175, 210, 220, 0.8);
+    position: absolute;
+    font-size: .9em;
+}
+#Sidenav input
+{
+    padding: 3px;
+    background-color: #fAfAfA;
+    border: 1px inset #999999;
+    outline: none;
+    float: right;
+    margin-right: 3%;
+    -moz-border-radius: 3px; -webkit-border-radius: 3px; border-radius: 3px;
+    box-sizing: border-box;
+    -moz-box-sizing: border-box;
+    -webkit-box-sizing: border-box;
+    position: relative;
+    max-width: 110px;
+}
+#Sidenav .closebtn
+{
+    position: absolute;
+    top: 10px;
+    right: 10px;
+    font-size: 25px;
+    margin-left: 50px;
+    cursor: pointer;
+    color: #000000;
+}
+
+canvas
+{
+    border: 1px solid #000000;
+}
+
+#login
+{
+    background: #bbbbbb;
+    z-index: 1;
+    padding-top: 2px;
+    border-bottom: 2px solid #00000040;
+}
+#login p
+{
+    margin-left: 27%;
+    display: inline;
+    font-size: large;
+}
+
+#spice-area
+{
+    height: 100%;
+    width: 100%;
+    margin-left: auto;
+    margin-right: auto;
+}
+.spice-screen
+{
+    min-height: 600px;
+    height: 100%;
+    text-align: center;
+    padding: 0;
+    background-color: #999999;
+}
+.spice-message
+{
+    width: 90%;
+    height: 40%;
+    overflow: auto;
+    margin-left: auto;
+    margin-right: auto;
+    padding: 10px;
+    font-size: 8pt;
+    line-height: 1.1em;
+    font-family: 'Andale Mono', monospace;
+    background-color: #fAfAfA;
+    border: 1px inset #999999;
+    border-radius: 3px;
+    box-sizing: border-box;
+    -moz-box-sizing: border-box;
+    -webkit-box-sizing: border-box;
+}
+.spice-message p {
+    margin-bottom: 0em;
+    margin-top: 0em;
+}
+.spice-message-warning {
+    color: orange;
+}
+.spice-message-error {
+    color: red;
+}