feat: move chess pieces by typing SQL queries + UI polish

[Copilot]

The app showed SQL for every move but never let players drive moves via SQL. This adds a full SQL input workflow and several UX improvements.

SQL Move Input

• New "Execute SQL Move" panel at the bottom of the SQL column
• Accepts the same UPDATE chess_piece SET position = '...' WHERE position = '...' format the app already generates, plus shorthand (e2 e4, e2-e4, e2 to e4, e2e4)
• Ctrl+Enter executes; parse/legality errors shown inline in red
• Promotions triggered via SQL fall through to the existing promotion dialog

-- Full form (matches generated schema)
UPDATE chess_piece
SET    position = 'e4'
WHERE  position = 'e2'
  AND  color    = 'white';

-- Shorthand
e2 e4

Auto-fill on piece click

Clicking a board piece pre-populates the textarea with a move template and positions the cursor on ??? (the destination placeholder), so typing the target square is the only remaining step.

UPDATE chess_piece
SET    position = '???'    -- cursor lands here
WHERE  position = 'e2'
  AND  color    = 'white';

Other UX changes

• Per-block ⎘ Copy button on every SQL log entry
• Active-turn glow — current player's bar gets a green border highlight
• Template textarea auto-clears after a successful board-click move or new game
• state.sqlInputHasTemplate flag tracks template state (avoids magic-string detection)