feat(web): segment watched/skipped action toggles

Watched and skipped are mutually exclusive (the store clears one when the other
is set), but rendered as three independent-looking buttons the exclusivity was
invisible. Group watched|skipped into a single segmented control and keep Saved
apart as an independent toggle (UX review C5). HTMX posting and the active/✓/
aria-pressed semantics are unchanged; extracted a shared actionButton component.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/web/views.templ

@@ -530,20 +530,31 @@ templ ActionButtons(videoID string, active map[string]bool) {
 		hx-target="#action-buttons"
 		hx-swap="outerHTML"
 	>
-		for _, v := range actionVerbs {
-			<button
-				type="submit"
-				name="action"
-				value={ v }
-				class={ "action", templ.KV("active", active[v]) }
-				aria-pressed={ ariaPressed(active[v]) }
-			>
-				if active[v] {
-					{ "✓ " + actionLabel(v) }
-				} else {
-					{ actionLabel(v) }
-				}
-			</button>
-		}
+		// watched ↔ skipped are mutually exclusive (the store clears one when the
+		// other is set), so they read as a single segmented choice. "saved" is an
+		// independent toggle and sits apart (UX review C5).
+		<span class="segmented" role="group" aria-label="Watched or skipped">
+			@actionButton("watched", active["watched"])
+			@actionButton("skipped", active["skipped"])
+		</span>
+		@actionButton("saved", active["saved"])
 	</form>
 }
+
+// actionButton is one toggle button in the action group: a submit carrying its
+// verb, marked active (accent fill + ✓ prefix + aria-pressed) when currently set.
+templ actionButton(verb string, isActive bool) {
+	<button
+		type="submit"
+		name="action"
+		value={ verb }
+		class={ "action", templ.KV("active", isActive) }
+		aria-pressed={ ariaPressed(isActive) }
+	>
+		if isActive {
+			{ "✓ " + actionLabel(verb) }
+		} else {
+			{ actionLabel(verb) }
+		}
+	</button>
+}