Keep the header and weight rows tidy when the age is long

The age counter can read "16 weeks (3 months and 3 weeks) old", which broke
two tight layouts: the header title never truncated, so a long name (or the
wide status pill) collided with the action buttons and the age wrapped to
three lines; and each weight-log row embedded the full age, wrapping to two
lines.

Add compact age formatters and use them where space is tight: formatAgeShort
("16 wk · 3 mo 3 wk") in the header, formatAgeWeeks ("16 wk") in weight rows;
the verbose form stays on the roomy weight-chart caption. Make the header
robust — the title flexes and the name ellipsis-truncates so the buttons are
never pushed, while the age wraps rather than truncating so it's never cut
off. Weight rows keep the date/age on one line with the value pinned right.

src/style.css

@@ -78,13 +78,24 @@ h1 {
   display: flex;
   flex-direction: column;
   gap: 2px;
+  flex: 1 1 auto;
   min-width: 0;
 }
+/* Truncate the name so a long one never runs into the action buttons. Scoped to
+   the header title so the auth-screen heading is unaffected. */
+#app-title {
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
 
 .puppy-age {
   font-size: 0.8rem;
   color: var(--muted);
   font-variant-numeric: tabular-nums;
+  /* One line in the common case; on a very narrow screen it wraps rather than
+     truncating, so the age is never cut off. The name (#app-title) is what
+     truncates to keep the buttons clear. */
 }
 
 .header-actions {
@@ -644,7 +655,16 @@ dialog menu {
 .weight-summary .stat-value.up   { color: var(--gain); }
 .weight-summary .stat-value.down { color: var(--danger); }
 .ww.weight-ww { cursor: pointer; }
-.ww.weight-ww .ww-dur { text-align: right; }
+/* Keep each weight row to one line: the date/age column shrinks and ellipses,
+   the weight value stays a fixed size, right-aligned and always visible. */
+.ww.weight-ww .ww-range {
+  min-width: 0;
+  flex: 1;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.ww.weight-ww .ww-dur { flex: 0 0 auto; text-align: right; }
 
 .legend {
   display: flex;