fix(home): send starter cards instead of filling the composer

Clicking today's reading or a topic card should open a consultation and wait for the model, not leave the question in the input box.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/DESIGN.md

@@ -172,12 +172,12 @@ The base unit is 4px. Tokens are `--space-1: 4px`, `--space-2: 8px`, `--space-3:
 - **Structure:** topic label, question, directional icon. Categories are not numbered because they have no required order. At tablet widths, the cards stack into one column so Chinese questions keep natural phrase boundaries beside the persistent sidebar.
 - **Surface:** warm light cards; the lead card uses the pale brown emphasis surface and border instead of a dark block.
 - **States:** default, hover, active, focus, disabled, loading, fallback notice.
-- **Visibility:** the initial cards, one per consultation domain, remain visible while the user types or chooses a question. They leave only after the question is submitted and the session receives its first user message.
+- **Visibility:** the initial cards, one per consultation domain, remain visible while the user types a custom question. Clicking a card starts that consultation immediately instead of filling the composer; the cards leave once the session receives its first user message.
 
 ### Product entrypoint card
 
 - **Structure:** the homepage daily-reading and birth-time cards are single native-button targets stretched across their article surface. Content remains semantic card copy; a compact action label and arrow sit at the lower right.
-- **Copy:** the composer and chat history show only the public labels “深入看今日”, “生时校正”, or “再次校正”. Private model instructions are selected by a closed entrypoint identifier and expanded only on the server.
+- **Copy:** chat history shows only the public labels “深入看今日”, “生时校正”, or “再次校正”. Clicking the daily card starts a consultation session with that public label and waits for the model; it does not place the question in the composer. Private model instructions are selected by a closed entrypoint identifier and expanded only on the server.
 - **States:** default, whole-card hover, pressed, focus-visible, and disabled. The card surface—not an inner promotional button—carries the interaction feedback.
 - **Responsive:** cards stack below 768px without introducing a large nested button; the footer keeps supporting copy flexible and the action label on one line.
 - **Accessibility:** each card exposes exactly one native button with a descriptive accessible name, preserves a visible focus ring, and meets the full-card touch target.