bug: Note symbol selection dropdown can't be scrolled on touch devices

## Summary When adding a new note, the **symbol selection dropdown cannot be scrolled on a touch interface**. The list of symbols opens, but touch-dragging inside the dropdown does not scroll it, so symbols below the initially visible ones are unreachable. This is worse with **"Show all symbols"** enabled, where the list is long enough that most symbols are off-screen. Freeboard runs on marine touchscreen chartplotters and tablets, where this is often the only input method, so the symbol picker is effectively unusable there. ## Steps to reproduce 1. On a touch device (tablet, phone, or touchscreen display), open Freeboard-SK. 2. Add a new note. 3. In the note dialog, tap the symbol/icon selector to open its dropdown. 4. Optionally enable **"Show all symbols"** to get the full list. 5. Try to scroll the dropdown by dragging with a finger. ## Expected The symbol dropdown scrolls with touch, exposing all symbols in the list. ## Actual The dropdown does not scroll under touch; only the symbols visible when it opens can be selected. ## Notes The selector is the Angular Material `mat-select` in the note dialog (`src/app/modules/skresources/components/notes/note-dialog.html`, the `<mat-select>` bound to `icon.svgIcon` / `poiIcons`). Its options render in a CDK overlay panel with a capped `max-height` and internal scroll region — a common spot for touch `touchmove` scrolling to fail inside the overlay. Reproduces most reliably once the option count exceeds the panel height (i.e. with "Show all symbols" on).