Dashboard: cleaner header tooltips, reservations info hover, swap-id search

[LandynDev]

Summary

• Depth of Market column headers: hover no longer shows the help-cursor question mark; uses pointer instead. The cursor: 'help' was the last lingering instance in the app.
• Reservations: added an info hover next to the section title with a short explanation of what a reservation is and why the step exists.
• Transactions search: typing #N or a bare digit string (e.g. #2, 2) now performs an exact swap-id lookup via the existing /swaps/:swapId endpoint, so swap Feat/realtime dashboard #2 actually surfaces instead of being buried by addresses that happen to contain the digit. Non-numeric input still uses the fuzzy multi-field search. Placeholder updated to hint the #N form.

Test plan

• Hover the Rate / Capacity / Cumulative column headers in Depth of Market — cursor is the pointer, no question-mark badge.
• Hover the info icon next to "Reservations" — tooltip shows the description.
• In Transactions search, type #2 (and 2) — swap Feat/realtime dashboard #2 appears as the only result. Type a partial address fragment — fuzzy results still work.