make Kanban view filter-able

[Kreisleriana]

One of the great things in Zennotes is its ability to collect tasks from anywhere in the vault. There are moments when focusing on a single project would be nice, though. This is currently possible but only in list view, not in calendar and notably not in Kanban view.

It would be great to be able to narrow down the number of visible tasks to those that are part of a project (inherited tag from project page) or text occurrence.

[adibhanna]

Built, and it lands in 2.30.0.

The filter box in the Tasks header now works in all three sub-views, not just the list. One query narrows the list, the calendar, and the Kanban board, and it survives switching between them, so you can filter once and move around. On the board it narrows the cards but keeps every column in place, the header shows 4 of 7 style counts, and a filtered board stays fully live: drag, Shift+H/L, and in-column reordering all work, and hand-arranged card order is preserved for the cards the filter is hiding.

For the focus-on-one-project part, the filter now also matches inline @key:value fields. So the flow is: tag tasks with @project:alpha, keep the board grouped by status, press /, type @project:alpha. That is a one-project board. Plain text and #tag matching cover your text-occurrence case.

Keyboard-wise: / focuses the filter (Vim mode), :filter <text> sets it from the ex line, and Esc clears it from anywhere in the view.

On the "inherited tag from project page" half: I deliberately did not implement frontmatter tag inheritance for inline tasks. It changes what tags a task carries everywhere (the task parser is mirrored across the app, the CLI, MCP, and the Go server), and the @project: field gives you the same focus with the label written on the task line itself. If inheritance still feels necessary after living with this for a bit, comment here and I will look at it as its own change.

Related: #222 asks for the same thing plus structured filter chips with AND/OR semantics; this covers the core, chips may come later.

Thanks for the nudge, this one was overdue.