docs(dialog-demo): update prose for polymorphic close

The dialog demo prose described "Six events" with the per-event close-*
shape that was collapsed into a single polymorphic close in commit
9f5fbfdb. Three updates:

- Header lede: "Eight parts; six events" → "Eight parts; two events
  (open + polymorphic close)" with the polymorphism rationale.
- morfo tab section: explains the imperative data-last-action +
  per-cause semantic pattern instead of the old per-event prewrite story.
- sema tab section: describes how dismissWith() swaps the family at
  trigger time per cause.
- Keyboard hint: "Close (close-dismiss)" → "Close (close with
  data-last-action='dismissed')" to match runtime behaviour.

The compiled events table at the bottom of the morfo tab auto-derives
from the morfo, so it already shows the correct collapsed event list
without modification.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/routes/uix/components/dialog/+page.svelte

@@ -148,10 +148,17 @@
 		<div data-uix-eyebrow>Overlays · Dialog</div>
 		<h1 data-uix-page-title>Dialog</h1>
 		<p data-uix-page-lede>
-			Modal blocking surface. Eight parts; six events with the full
+			Modal blocking surface. Eight parts; two events
-			asymmetric exit set (saved · cancelled · dismissed · dismissed-outside
+			(<code>open</code> + a polymorphic <code>close</code>) with the
-			· failed) surfaced via <code>data-last-action</code>. Modal subset of
+			full asymmetric exit set (saved · cancelled · dismissed ·
-			intent — only <code>neutral</code> / <code>risk</code> /
+			dismissed-outside · failed) surfaced via
+			<code>data-last-action</code>. The provider concretes the
+			<code>close</code> event's family at trigger time —
+			<code>emerge.close</code> (cancel / dismiss / dismiss-outside),
+			<code>commit.save + fulfill</code> (save) or
+			<code>signal.alert + threat</code> (fail) — per book §5.3
+			polymorphism. Modal subset of intent — only
+			<code>neutral</code> / <code>risk</code> /
 			<code>threat</code>; affirm / fulfill / loss are intentionally
 			off the table per the modal canon.
 		</p>
@@ -455,12 +462,16 @@
 				· declarative contract
 			</h2>
 			<p data-uix-section-desc>
-				Source: <code>src/uix/morfo/components/dialog.ts</code>. Six
+				Source: <code>src/uix/morfo/components/dialog.ts</code>. Two
-				events surface five distinct exit reasons via
+				events — <code>open</code> (intent-bound via fromProp) and
-				<code>data-last-action</code> prewrites. open is intent-bound;
+				a polymorphic <code>close</code> (book §5.3) with
-				close-cancel / close-dismiss / close-dismiss-outside drop the
+				<code>allowedFamilies: ['emerge', 'commit', 'signal']</code>.
-				intent (backing out has no evaluative load); close-after-fail
+				The provider sets <code>data-last-action</code> imperatively
-				explicitly carries threat regardless of provider intent.
+				before each close and passes the concrete semantic per cause:
+				cancel / dismiss / dismiss-outside fire as plain emerge
+				(backing out has no evaluative load); save fires as
+				commit.save + fulfill; fail fires as signal.alert + threat
+				regardless of provider intent.
 			</p>
 
 			<div data-uix-table-wrap>
@@ -588,14 +599,17 @@
 				· events + perceptual signature
 			</h2>
 			<p data-uix-section-desc>
-				Six events. <code>open</code> is fromProp-bound to the
+				Two events. <code>open</code> is fromProp-bound to the
 				provider's <code>intent</code> — a threat dialog opens with
-				threat-flavoured perceptual weight. close-save consummates as
+				threat-flavoured perceptual weight. <code>close</code> is
-				fulfill (the user committed). close-cancel /
+				polymorphic (book §5.3) — the table shows its declared
-				close-dismiss-* drop intent (no evaluative load on backing
+				default family (<code>emerge</code>); the runtime swaps the
-				out). close-after-fail explicitly hits threat regardless of
+				family per cause via <code>opts.semantic</code> in
-				provider intent. Click <strong>play</strong> to fire on the
+				<code>dismissWith()</code>: save → commit.save + fulfill;
-				live dialog.
+				cancel / dismiss / dismiss-outside → emerge.close (no
+				evaluative load on backing out); fail → signal.alert +
+				threat regardless of provider intent. Click
+				<strong>play</strong> to fire on the live dialog.
 			</p>
 
 			<div data-uix-table-wrap>
@@ -671,7 +685,7 @@
 					<thead><tr><th>Key</th><th>Action</th></tr></thead>
 					<tbody>
 						<tr><td><span data-uix-kbd>Enter</span> / <span data-uix-kbd>Space</span></td><td>Open from Trigger.</td></tr>
-						<tr><td><span data-uix-kbd>Escape</span></td><td>Close (close-dismiss).</td></tr>
+						<tr><td><span data-uix-kbd>Escape</span></td><td>Close (close with data-last-action='dismissed').</td></tr>
 						<tr><td><span data-uix-kbd>Tab</span> / <span data-uix-kbd>Shift+Tab</span></td><td>Cycle focus inside Content.</td></tr>
 					</tbody>
 				</table>