Settings: fix mouse desync in scrolled search results and wheel reach of the last result

[sinelaw]

Fixes #2860
Refs #1112

Motivation

In the Settings dialog's search mode, mouse interaction desyncs as soon as the result list is scrolled (#2860):

1. Only the visible result rows are registered in the hit-test layout, so hit_test returned a viewport-slot index (0 = first visible row) while its consumers (hover compare in the renderer, click handler) treat the value as an absolute index into search_results. After scrolling, hover highlighted — and clicks activated — the result search_scroll_offset rows above the pointer.
2. Wheel-scrolling clamps the offset at len - max_visible and pins the selection to the viewport edge, so at the end of the list further wheel-downs were no-ops and the last result could never be selected with the wheel (keyboard reaches it fine).

The fix

• SearchResultLayout now stores the absolute result index each visible row was registered with, and hit_test returns that, so hover/click stay in the same index space as the state regardless of scrolling. The web frontend already sends absolute indices for searchResult hits, so it is unaffected.
• search_scroll_down keeps advancing the selection once the viewport is at the bottom (until the last result), and search_scroll_up symmetrically walks the selection up to the first result at the top — matching keyboard navigation.

#1112 (remaining mouse half)

The recent status sweep on #1112 reported that clicks on scalar controls (Number value cell, Toggle checkbox, Dropdown button) are inert. I could not reproduce that at HEAD: driving the debug build in tmux (200x50 and 120x40) and in the e2e harness, clicking the value cell starts inline editing, clicking a checkbox flips it, and clicking a dropdown button opens the inline option list — the widget-derived hit rects are registered at the correct screen cells. (The -/+ number buttons from the original report were removed by design in favor of direct typing.) Since only the Number value-cell click had e2e coverage, this PR adds regression coverage for the Toggle and Dropdown click paths so the working behavior is pinned down.

Tests

New reproducers (all fail without the fix commits, pass with them):

• view::settings::layout::tests::test_hit_test_search_result_scrolled_uses_absolute_index (unit)
• view::settings::state::tests::test_search_wheel_down_reaches_last_result, test_search_wheel_up_reaches_first_result (unit)
• e2e::settings::test_settings_search_result_click_after_wheel_scroll, test_settings_search_wheel_selects_last_result (e2e, rendered-output assertions only)

New regression coverage (passes before and after; pins existing behavior for #1112):

• e2e::settings::test_settings_toggle_checkbox_click_flips_value, test_settings_dropdown_button_click_opens_options

Ran:

• cargo test -p fresh-editor --lib view::settings — 112 passed
• cargo test -p fresh-editor --test e2e_tests -- e2e::settings — 124 passed, 0 failed (2 pre-existing ignored)
• cargo check --all-targets -p fresh-editor, cargo fmt, cargo clippy -p fresh-editor --tests — clean on touched files
• Manual tmux validation of the debug build: search "line", one wheel notch, hover/click lands on the row under the pointer; wheel to the end selects the last result (219 of 219); Tab Size value-cell click enters inline editing.

🤖 Generated with Claude Code

https://claude.ai/code/session_01D6SkGXXTcJsytTjF1TBf8Y

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