feat: in-view resource search/filter and column sorting

[Bccorb]

Problem

The command palette only fuzzy-matches view names; no view offers in-list filtering/search or sorting of resource rows. This is the scaling gap the roadmap calls out.

Evidence

• palette matches views only: src/ui/views/command.rs
• no filter state in App

Impact

Numeric keys + Tab-cycling do not scale as rows/services grow.

Proposed fix

Add a per-view fuzzy row filter and sortable columns (best built on the shared list helper #30).

Acceptance

• Operators can filter and sort rows within a view

[Bccorb]

Re-checked against current main. The filter half is done; column sorting is untouched.

Done: m opens a per-view row filter with live match counts, case-insensitive substring matching over the fields each view displays. It routes through the service registry rather than the view layer, so describe, open, CLI, and Enter all act on the row actually highlighted. An empty result explains that a filter caused it.

Not done: there is no runtime column sorting anywhere. Every sort_by in the tree is a fixed compile-time order (fetch-time sorts in the service fetchers, severity ordering in build_findings, spend ranking in sorted_cost_insights). There is no sort_column or SortOrder state on App and no key bound to a sort action.

Sorting was left out deliberately rather than missed: it needs per-view sortable column definitions and a cycle/direction UI, which is a separate axis from filtering and would have roughly doubled that change. This issue should stay open for it.

One thing worth deciding when sorting is built: selected_row indexes the rows on screen and is resolved back to a resource through App::visible_indices. A sort has to reorder that same projection, not just the rendered rows, or the selection will point at the wrong resource. That is the bug the filter work had to avoid, and sorting will hit it identically.