docs(site): show all six themes, and put the demo line in English

Adds a gallery of the same Today view in each of the six themes — Northern lights,
Charcoal, Dusk, Daylight, Paper, Contrast — so the range is shown rather than
described, on the landing page and (as the swatch panel) the docs home. The lone
Charcoal Today capture is folded into it.

And the quick-add demo that leads the docs — "betal moms i morgen kl 10 p1 #Firma
@regnskab" — is now English, "file the VAT return tomorrow at 10am p1 #Accounts
@tax", on every page it appears as the line to type: the home, the quick-add page,
the API and MCP examples, and the OpenAPI blurb. The Danish date words on the
quick-add page stay, because documenting the Danish parser is their job.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/index.md

@@ -18,9 +18,10 @@ forward mail to, and an MCP endpoint so Claude can work your task list directly.
 
 ## What it does
 
-- **[Quick add](quick-add.md) that reads what you type.** `betal moms i morgen kl
-  10 p1 #Firma @regnskab` becomes a task due tomorrow at 10:00, priority 1, in
-  Firma, labelled regnskab. Danish and English, mixed freely in one line.
+- **[Quick add](quick-add.md) that reads what you type.** `file the VAT return
+  tomorrow at 10am p1 #Accounts @tax` becomes a task due tomorrow at 10:00,
+  priority 1, in Accounts, labelled tax. Danish and English, mixed freely in one
+  line.
 - **Projects, sections, sub-tasks, labels, [saved filters](filters.md).** List,
   board and calendar views, and foldable groups over the projects in the sidebar.
   The calendar draws each task to its length — drag the foot to resize, the body
@@ -72,8 +73,12 @@ meet it.*
 ![Notes in the Charcoal theme](screenshots/notes-charcoal.png)
 
 *Charcoal, the newest of six themes — a warm near-black after Apple Notes, with
-amber where the accent green usually is. Three dark themes and three light, and a
-typeface and size chosen apart from them.*
+amber where the accent green usually is.*
+
+![The six themes as swatches](screenshots/themes.png)
+
+*Six themes — three dark, three light — chosen on the settings page, with the
+typeface and how tightly it sits set apart from them.*
 
 ![Settings, integrations](screenshots/settings.png)