Add PWA service worker (via vite plugin), use dynamic viewport units for interface size (improves mobile experience), replace default vue homepage with basic info

frontend/src/assets/base.css

@@ -82,7 +82,7 @@
 }
 
 body {
-  min-height: 100vh;
+  min-height: 100lvh;
   color: var(--color-text);
   background: var(--color-background);
   transition:

frontend/src/assets/main.css

@@ -2,6 +2,34 @@
 
 *[hidden] { display: none !important; }
 
+body {
+  display: flex;
+  direction: row;
+}
+
+main {
+  height: 100dvh;
+  flex-grow: 1;
+  overflow: auto;
+}
+
+.main-sidebar {
+  height: 100dvh;
+  display: flex;
+  flex-direction: column;
+  position: relative;
+  z-index: var(--z-index-sidebar);
+  background-color: var(--color-background);
+}
+
+.main-header {
+  height: 3em;
+  border-bottom: 1px solid var(--color-border);
+  display: flex;
+  flex-direction: row;
+  align-items: center;
+}
+
 a {
   text-decoration: none;
   color: var(--color-blue);
@@ -20,17 +48,6 @@ button {
   border-color: var(--color-border-hover);
 }
 
-body {
-  display: flex;
-  direction: row;
-}
-
-main {
-  height: 100vh;
-  flex-grow: 1;
-  overflow: auto;
-}
-
 .with-sidebar-expanded .when-sidebar-collapsed {
   display: none;
 }