Polish sticky headers, Custom View, docs page and dialogs

- Status tables: the whole header (column names + filters) sticks as one
  block, tucked 1px under the group header, so no gap can open between
  the rows; offsets use fractional heights
- Phones/tablets: the filter panel sticks under the group header too, and
  is opaque and compact (three filters per row on phones)
- Custom View: fix the group header being pushed over the column header
  (it lives inside the view's own scroll box); the column header now pins
  to the top of that box on desktop, and the header strip sticks on phones
- All Devices: group title is "All Devices (N)" instead of "Missing
  Software", matching the page title count
- Documentation fits the window on desktop: only the article list and the
  article scroll; placeholder no longer says "from the left"
- Dialogs sit above the terminal dock so it can't cover their last rows;
  page bottom padding follows the dock's measured height

web/layout.js

@@ -87,16 +87,19 @@
         return null;
     }
     function updateSticky() {
+        const root = document.documentElement;
         const nav = document.querySelector('.top-nav');
-        const navH = nav ? nav.offsetHeight : 60;
-        setVar(document.documentElement, '--nav-h', navH + 'px');
+        const navH = nav ? nav.getBoundingClientRect().height : 60;
+        setVar(root, '--nav-h', navH + 'px');
+        const dock = document.getElementById('usmt-term');
+        setVar(root, '--dock-h', (dock ? Math.ceil(dock.getBoundingClientRect().height) : 0) + 'px');
+
         document.querySelectorAll('table.master-table').forEach(table => {
+            if (!table.offsetParent) return;                    // hidden page/group: keep old values
             const gh = groupHeaderFor(table);
-            const ghH = gh ? gh.offsetHeight : 0;
-            const firstRow = table.tHead && table.tHead.rows[0];
-            if (!firstRow || !firstRow.offsetHeight) return;   // hidden page/group: keep old values
-            setVar(table, '--sticky-top', (navH + ghH) + 'px');
-            setVar(table, '--thead-r1', firstRow.offsetHeight + 'px');
+            const ghH = gh && getComputedStyle(gh).position === 'sticky' ? gh.getBoundingClientRect().height : 0;
+            // 1px overlap tucks the table header under the group header: no hairline gap
+            setVar(table, '--sticky-top', Math.max(0, navH + ghH - 1) + 'px');
         });
     }
 
@@ -121,6 +124,14 @@
         // Groups and pages are shown by toggling display (not a DOM change), so also
         // re-measure as the user scrolls; writes only happen when a value changes.
         window.addEventListener('scroll', schedule, { passive: true });
+        // The terminal dock opens, closes and resizes without a page resize
+        if (window.ResizeObserver) {
+            const watchDock = () => {
+                const dock = document.getElementById('usmt-term');
+                if (dock) new ResizeObserver(schedule).observe(dock); else setTimeout(watchDock, 500);
+            };
+            watchDock();
+        }
         schedule();
     }
     if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', start);