fix(view,place): the boards view pads clear of the phone's navbar

The panel had an inset for this; the calendar never did. Its root filled the
leaf, and Obsidian's phone navbar floats over a leaf rather than shortening
it, so the scroll container ran to the bottom of the screen and the last row
of the list sat under the bar - unreachable.

`lib/inset.ts` is the same pure measurement the panel plugin grew, with the
same tests: the deeper of navbar and keyboard, never their sum, and a bar that
sits beside the view covers nothing of it. The view re-measures by frame until
it holds still and writes `--bcal-inset-bottom`.

`viewport()` subtracts the bar too, so anchored panels and the quick look are
placed against what is actually reachable instead of ending under it.

src/tailwind.css

@@ -102,7 +102,12 @@
 }
 
 .bcal-root {
+  box-sizing: border-box;
   height: 100%;
+  /* The phone's navbar floats over the leaf rather than shortening it, so the
+     last row of the list would sit underneath it. The view measures how much
+     and sets this; on a desktop it stays 0. */
+  padding-bottom: var(--bcal-inset-bottom, 0px);
   font-family: var(--font-interface);
   font-size: var(--text-sm);
   color: var(--foreground);