fix: remove em dashes and tighten copy in home and about pages

Fixes found in unslop-text audit:
- Home page: em dash in hero description (diagram—great → diagram, great)
- About lede: em dash before list (text — for → text: )
- About partners: we/I voice flip, "happily" adverb, spaced-hyphen-as-dash

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dani-polani

bitext/src/routes/+page.svelte

@@ -267,7 +267,7 @@
 				>
 					See exactly which word matches which across stacked lines. Add rows for glosses or IPA if
 					you need them, click a word then its match on the line above or below, and export or share
-					the diagram—great for lessons, posts, or conlang notes.
+					the diagram, great for lessons, posts, or conlang notes.
 				</p>
 				<p class="mt-4 max-w-prose text-sm leading-relaxed text-gray-600 dark:text-gray-400">
 					Created by

bitext/src/routes/about/+page.svelte

@@ -244,7 +244,7 @@
 	<p class="mt-4 text-lg text-gray-600 dark:text-gray-400">
 		<strong class="font-semibold text-gray-800 dark:text-gray-200">{DISPLAY_NAME}</strong> is a free,
 		browser-based tool for drawing word-to-word and morpheme-to-morpheme links between stacked lines of
-		text — for bilingual glosses, interlinear annotations, classroom handouts, and social posts. Everything
+		text: bilingual glosses, interlinear annotations, classroom handouts, and social posts. Everything
 		runs in your browser; your sentences are not stored on our servers unless you choose to share them.
 	</p>
 
@@ -453,9 +453,9 @@
 	<h2 id="doc-partners" class={headingClass}>Partner links</h2>
 	<p class="mt-3">
 		{DISPLAY_NAME} stays free and without aggressive ads. Hosting and ongoing upkeep still have a cost,
-		so we add a few optional partner links - use them if you were already considering the service. It
-		will help us keep the site running. The referral bonuses come from the provider. Here I recommend
-		the services that I happily use myself.
+		so I add a few optional partner links. Use them if you were already considering the service; it
+		helps keep the site running. The referral bonuses come from the provider. These are services I use
+		myself.
 	</p>
 	<div class="mt-5 flex min-w-0 flex-col gap-4">
 		<PartnerBannerPreply />