fix: Navigate button (geocode-bar) missing from peek pointer-events opt-in; search dropdown stays open after Navigate here

[jasoneplumb]

Symptoms (after v0.31.2-beta)

1. Long-press → tap Navigate (in geocode-bar) doesn't respond.
   The Navigate button is inside the bar's body. In peek state, the bar has pointer-events: none and only specific children opt back in via:

   .geocode-bar--peek .geocode-bar__handle,
   .geocode-bar--peek .geocode-bar__copy,
   .geocode-bar--peek .geocode-bar__close,
   .geocode-bar--peek .geocode-bar__addr { pointer-events: auto; }

   .geocode-bar__nav is missing from this list, so on mobile Safari (where pointer-events: none propagation to children is browser-quirky) Navigate doesn't receive taps. Without Navigate firing, hideGeocodeBar() from fix(guidance): hide geocode-bar when starting navigation so Stop is tappable (#175) #176 doesn't run, the bar stays open, and Stop is also blocked.

2. Search → "Navigate here" → Stop doesn't respond.
   The search dropdown (.search-dropdown, z-index: 2000) stays visible after Navigate here — its handler at geocoding.ts:246 calls startGuidance but never closes the dropdown. On smaller viewports the dropdown can overlap the bottom-left guidance pill area, and even when it doesn't, leaving stale UI is bad UX.

Fix

1. Add .geocode-bar__nav to the peek-state pointer-events: auto opt-in list.
2. Call hideDropdown() from the search dropdown's Navigate here click handler before startGuidance().

Acceptance

• Long-press → Navigate (in bar): button responds, bar hides, guidance starts
• Long-press → Navigate → Stop: Stop responds (no overlap)
• Search → Navigate here: dropdown closes, guidance starts
• Search → Navigate here → Stop: Stop responds (no stale dropdown)