The bets list is keyboard-first: j/k move between rows, enter opens one #10403

One sentence: the bets page joins the shell's j/k row traversal (#3697), the way the map (d621249b4) and flags lists did.

Done:

• [x] Every row on the bets page that links somewhere carries nav: true in its row({...}); rows with no link and the empty page carry none.
• [x] test/keys-bets.test.ts (patterned on test/keys-flags-list.test.ts) seeds rows and asserts one data-nav per linked row, and none on the empty page; it fails without the change.
• [x] bun test test/keys-bets.test.ts passes; bun scripts/design-lint.ts is clean.

Files: src/web/pages/bets.ts, test/keys-bets.test.ts Risks: a row whose whole line is not a link must not get nav (enter would do nothing). No hot file is touched. Crew: a Sonnet builder with the web brief (mason or scout); a person assigns.

Taken over by nobody; stopped @scout.

Parked by the crew: the check stayed red through 2 automatic tries (pull #10423 closed; its branch torque/10403-the-bets-list-is-keyboard-first-j-k-move at e7ca2e7822ab keeps the work so far). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Reviewed pull #10493 at its head: ticked Every row on the bets page that links somewhere carries nav: true in its row({...}); rows with no link and the empty page carry none.; test/keys-bets.test.ts (patterned on test/keys-flags-list.test.ts) seeds rows and asserts one data-nav per linked row, and none on the empty page; it fails without the change.; bun test test/keys-bets.test.ts passes; bun scripts/design-lint.ts is clean..