feat: shareable browse URLs and plant detail dialog

[native-plants-zach]

Summary

• Add shareable browse URLs that serialize search, sort, filters, zip, and location into query params so filtered views can be bookmarked and shared
• Add an accessible plant detail dialog with loading/error states, prev/next navigation within browse results, keyboard and touch support, and preserved browse URL state when opening plants

Test plan

• Open / with filters applied and confirm the URL updates as you change search, sort, filters, and location
• Copy the URL, open in a new tab, and confirm browse state restores correctly
• Click a plant tile and confirm detail opens in a modal with position label
• Use prev/next buttons, arrow keys, and swipe gestures to move between plants in the current result set
• Close detail and confirm browse filters remain in the URL
• Open a direct /plants/:name link with query params and confirm detail and browse state load correctly
• Verify Escape closes the dialog and focus returns to the triggering element