shell themes: add Daylight — bottom-anchored, segmented, light builtin

Fourth compiled-in shell theme (bread-theme/src/shell/builtin.rs). Stresses
four axes no existing theme touched:

- light surfaces (new tokens.light flag, swaps which of the fixed @bg/
  @on-bg pair plays paper-surface vs ink — see Tokens::light's doc comment)
- bottom anchoring (bar.window.anchors = ["bottom", ...])
- segmented bar chrome (new bar_border = "segmented" value: the bar window
  itself draws no fill/border, three slot-group pills draw their own)
- blur disabled per-theme ([compositor.*] blur = false everywhere)

Also: a new bottom_right surface anchor (manifest.rs + types.rs), since the
three existing anchor shapes all assume a top-anchored bar's satellites
belong in the top-right corner. tokens.accent2() gives the equaliser its
own accent independent of accent_from/accent_to.

bread-theme/assets/shell/daylight/daylight.css

@@ -0,0 +1,117 @@
+/* CSS template for the daylight builtin (bread-theme/src/shell/builtin.rs).
+ * Same scope and substitution rules as its three siblings: only the
+ * window/workspace/clock chrome the manifest's own concepts model, `{name}`
+ * tokens substituted, `@name` palette references passed through untouched.
+ * Declared-but-not-yet-consumed in production, same as every sibling
+ * template — see `ShellTheme::css`'s doc comment for why (breadbar hand-
+ * rolls its own CSS in `breadbar::theme::load_css` instead of calling this
+ * method). Exercised by this crate's own tests.
+ *
+ * Source: bos-ui-demos/proposed/daylight.html's <style> block.
+ *
+ * Unlike its three siblings, this template hardcodes which of `@bg`/`@on-bg`
+ * plays "paper surface" versus "ink" directly (`@on-bg` as the fill, `@bg`
+ * as the text) rather than branching on `{light}` at substitution time —
+ * `Tokens::substitute` only does `{name}` replacement, not conditionals, and
+ * this template is Daylight's alone, so there is nothing to branch FOR here.
+ * `breadbar::theme::load_css` is the one place that genuinely needs to pick
+ * between the two directions at runtime (it renders all four themes from
+ * one function) — see its own `panel`/`ink` locals and Tokens::light's doc
+ * comment for the general mechanism this template only needs one side of.
+ */
+
+window.breadbar {
+  background-color: transparent;
+  border: none;
+  box-shadow: none;
+  color: @bg;
+}
+window.breadbar > box > centerbox { padding: 0 14px; }
+window.breadbar button { min-height: 0; min-width: 0; }
+
+/* The three detached pills (axis 3, segmented) — see
+ * breadbar::theme::load_css's `.bar-segment` rule for the identical
+ * production version of this block.
+ */
+.bar-segment {
+  background-color: alpha(@on-bg, {bg_alpha});
+  border: 1px solid alpha(@bg, 0.10);
+  border-radius: {radius_bar}px;
+  box-shadow: 0 2px 10px alpha(@bg, 0.13);
+}
+
+.workspace-trail {
+  background-image: linear-gradient(90deg, @{accent_from}, @{accent_to});
+  background-color: @{accent_from};
+  border-radius: {radius_sm}px;
+}
+.workspace-btn {
+  background: transparent;
+  opacity: 0.36;
+  color: @bg;
+  border-radius: {radius_sm}px;
+  border: none;
+  outline: none;
+  box-shadow: none;
+  min-width: 28px;
+  min-height: {chip_height}px;
+  margin: 0;
+  padding: 0 7px;
+  font-size: 22px;
+  font-weight: bold;
+  transition: opacity 0.22s {spring_settle}, background-color 0.22s {spring_settle};
+}
+.workspace-btn:hover { opacity: 0.85; background: alpha(@bg, 0.08); }
+.workspace-btn.occupied { opacity: 0.78; }
+.workspace-btn.active { background: transparent; color: @on-accent; opacity: 1; }
+.workspace-btn.active:hover { background: transparent; }
+
+.clock-plain { padding: 0 4px; }
+.clock-plain-time {
+  font-size: {font_size_base}px;
+  font-weight: 600;
+  letter-spacing: 0.04em;
+}
+.date-label {
+  font-size: 12px;
+  opacity: 0.48;
+  font-weight: 400;
+  letter-spacing: 0.04em;
+}
+
+/* Warm amber equaliser — the second accent (axis 1's colour-mapping note):
+ * distinct from the teal workspace-trail accent above.
+ */
+.media-eq-bar {
+  background-color: @{accent2};
+}
+
+/* Light-theme overrides of the notification/OSD surfaces — the demo's own
+ * `.notifs`/`.note`/`.osd` block, which explicitly replaces shared.css's
+ * dark defaults. `@on-bg` (paper) / `@bg` (ink), not `@bg` (glass) / `@on-bg`
+ * (light ink) the way every sibling theme's identical rule reads — this is
+ * the one deliberate inversion this template makes relative to its
+ * siblings, and it is exactly what `{light}` conditions in the shared Rust
+ * implementation (breadbar::theme::load_css). See axis 1 in the task
+ * report for the full inventory this one inversion stands in for.
+ */
+window.breadbar-osd {
+  background-color: alpha(@on-bg, {bg_alpha});
+  color: @bg;
+  border-radius: {radius_pill}px;
+  border: 1px solid alpha(@bg, 0.10);
+  box-shadow: 0 8px 22px alpha(@bg, 0.16);
+}
+
+window.breadbar-panel {
+  background-color: alpha(@on-bg, {bg_alpha});
+  color: @bg;
+  border-radius: {radius_card}px;
+  border: 1px solid alpha(@bg, 0.10);
+}
+
+window.breadbar-dismiss {
+  background-color: alpha(#000000, 0.02);
+}
+
+.bread-widget-slot { margin-right: {pad}px; }