A pin on the title bar, and no more notch

Pointing at a tile's top edge already brings its bar back, which left the
notch doing half a job: it could still hide a bar, but hiding one tile at a
time stopped being the interesting question once the whole dashboard could
fold its bars at once. It is gone.

In its place, a pin beside each tile's label. Pinned, that tile keeps its
bar while auto-hide is on — for the one or two tiles whose controls are
wanted at a glance. It sits next to the label rather than out with the gear
and ✕ because it is about the bar, not about the tile's contents, and it
stays faint until the tile is pointed at or the pin is on, so a wall of
unpinned tiles is not a wall of pins.

Fullscreen keeps its own rule: every bar folds, pinned or not, because that
is a mode for watching. What it loses with the notch it gets back better —
the same hover at a tile's top edge peeks a bar there too, and now as an
overlay, so peeking no longer pushes the tile's content down and disturbs
the auto-fit. The peek timer the notch needed goes with it.

Per-tile `headHidden` gives way to `headPinned` in the layout, on disk and
on the server.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

public/style.css

@@ -284,7 +284,7 @@ body.menu-hidden #topbar {
    Pointing at the tile's top edge slides it back in over the content
    (shell.js adds .head-peek) — and because it is the same element, its
    buttons click and its width drags the tile just as they always did. */
-body:not(.fullscreen) .tile.head-off > .tile-head {
+.tile.head-off > .tile-head {
   position: absolute;
   top: 0;
   left: 0;
@@ -298,17 +298,14 @@ body:not(.fullscreen) .tile.head-off > .tile-head {
   pointer-events: none;
   transition: transform 0.18s ease, opacity 0.18s ease;
 }
-body:not(.fullscreen) .tile.head-off.head-peek > .tile-head {
+.tile.head-off.head-peek > .tile-head {
   transform: none;
   opacity: 1;
   pointer-events: auto;
 }
-body:not(.fullscreen) .tile.is-tinted.head-off > .tile-head {
+.tile.is-tinted.head-off > .tile-head {
   background: color-mix(in srgb, var(--tile-tint) 20%, var(--panel));
 }
-/* Auto-hide already reveals on hover, so the notch would be a dead control;
-   a bar this tile hid by itself keeps its notch, which is how it comes back. */
-body.autohide-heads .tile-notch { display: none; }
 
 .tile-head .dot {
   flex: none;
@@ -323,7 +320,7 @@ body.autohide-heads .tile-notch { display: none; }
 .tile-head .dot.error { background: var(--danger); }
 
 .tile-title {
-  flex: 1;
+  flex: 0 1 auto;
   min-width: 0;
   font-size: 12px;
   font-weight: 700;
@@ -354,6 +351,33 @@ body.autohide-heads .tile-notch { display: none; }
 .tile-btn.is-open,
 .tile-btn.is-open:hover { background: var(--accent); color: var(--accent-text); }
 
+/* The pin: a state, not an action, so it stays quiet until it is on and
+   sits closer to the label than to the buttons at the other end. It fades
+   in with the rest of the tile's chrome so a wall of unpinned tiles is not
+   a wall of pins. */
+.tile-btn.pin {
+  width: 18px;
+  height: 18px;
+  margin-left: 2px;
+  opacity: 0;
+  transition: opacity 0.15s ease;
+}
+.tile-btn.pin svg { width: 12px; height: 12px; }
+.tile:hover .tile-btn.pin,
+.tile-btn.pin:focus-visible { opacity: 0.75; }
+.tile-btn.pin:hover { opacity: 1; }
+/* Pinned reads at a glance, whether or not anything is being pointed at. */
+.tile-btn.pin.is-pinned,
+.tile:hover .tile-btn.pin.is-pinned {
+  opacity: 1;
+  color: var(--accent);
+}
+.tile-btn.pin.is-pinned .pin-head { fill: currentColor; }
+.tile-btn.pin.is-pinned:hover { background: var(--border); }
+
+/* Keeps the label hugging its pin however wide the tile is. */
+.tile-head-gap { flex: 1 1 auto; min-width: 0; }
+
 /* the shell's tooltip: shown at once under the button the pointer is on */
 #tip {
   position: fixed;
@@ -407,55 +431,6 @@ body.autohide-heads .tile-notch { display: none; }
 }
 .tile-menu[hidden] { display: none; }
 
-/* notch on the title bar's bottom edge: click to hide/show the bar
-   (same idea as the ProdCom Listener's pull-down menubar handle) */
-.tile-notch {
-  position: absolute;
-  top: 32px;
-  left: 50%;
-  transform: translateX(-50%);
-  width: 46px;
-  height: 13px;
-  padding: 0;
-  background: var(--panel);
-  border: 1px solid var(--border);
-  border-top: none;
-  border-radius: 0 0 10px 10px;
-  cursor: pointer;
-  z-index: 6;
-  opacity: 0;
-  transition: opacity 0.15s ease, top 0.22s ease;
-}
-.tile:hover .tile-notch { opacity: 0.6; }
-.tile .tile-notch:hover { opacity: 1; }
-body:not(.fullscreen) .tile.head-off .tile-notch { top: 0; }
-.tile-notch::after {
-  content: "";
-  display: block;
-  width: 18px;
-  height: 3px;
-  margin: 4px auto 0;
-  border-radius: 999px;
-  background: var(--muted);
-}
-.tile-notch:hover::after { background: var(--text); }
-
-/* Fullscreen is for watching, not arranging: every title bar folds away, and
-   a tile's own hidden/shown preference is left untouched for when the screen
-   comes back. The notch still peeks one open, and it folds back once the
-   pointer has been off that tile for a while (PEEK_HIDE_MS in shell.js). */
-body.fullscreen .tile:not(.head-peek) .tile-head {
-  height: 0;
-  border-bottom-width: 0;
-  overflow: hidden;
-}
-body.fullscreen .tile:not(.head-peek) .tile-notch { top: 0; }
-body.fullscreen .tile.head-peek .tile-head {
-  height: 32px;
-  border-bottom-width: 1px;
-}
-body.fullscreen .tile.head-peek .tile-notch { top: 32px; }
-
 .tile-body {
   flex: 1;
   position: relative;