search injects default board, breaking cross-board tag/assignee filters

[waynemsmith]

Problem

fizzy search calls defaultBoard(searchBoard) which falls back to the configured default board when --board is not passed. This silently scopes every search to a single board, making --tag and --assignee filters appear broken when matching cards exist on other boards.

Example: Card #504 is on the "Delta Scope" board and tagged delta-scope. With default board set to "Dev":

# Returns 0 results — searches only Dev board
fizzy search "progressive" --tag 03fm8v7rpvvjnt2y7swbkfqos

# Works — explicitly targets the right board
fizzy search "progressive" --board 03f78lv1yjoyyz65hd6c3k557 --tag 03fm8v7rpvvjnt2y7swbkfqos

The API itself supports cross-board search (confirmed via direct curl).

Root cause

internal/commands/search.go line 46:

boardID := defaultBoard(searchBoard)

defaultBoard() returns the config default when the flag is empty. For card list this makes sense (list needs a board). For search, it should be cross-board by default.

Fix

Only add board_ids[] when --board is explicitly passed:

// Before
boardID := defaultBoard(searchBoard)
if boardID != "" {
    params = append(params, "board_ids[]="+boardID)
}

// After
if searchBoard != "" {
    params = append(params, "board_ids[]="+searchBoard)
}

PR incoming.