fix: raise mobile sidebar touch targets to 44px minimum

[atomantic]

What

Every primary navigation link, database disclosure button, drawer close button, and the theme toggle in the mobile sidebar now render at a 44x44px minimum, matching the 44px hamburger that opens the drawer (previously these controls were 40px, or had no explicit minimum in the theme toggle's case).

Changes

• navLinkClasses (covers all primary and nested links): min-h-[40px] → min-h-[44px]
• Database disclosure button: min-h-[40px] → min-h-[44px]
• Mobile drawer close button: min-h-[40px] min-w-[40px] → min-h-[44px] min-w-[44px]
• Theme toggle: added min-h-[44px] so all drawer controls share one consistent target-size rule

Icon/label layout and the scrollable nav region are unchanged; the scrollable region keeps everything reachable with many databases.

Test plan

• npm run build -w shared && npm run build -w client passes (tsc -b + vite build)
• At 360x640, open the drawer: top nav links, database expanders, close button, and theme control each render ≥44px tall
• At 768x1024 / 1280x800, desktop sidebar behavior is unchanged (same classes apply, only min-height raised)

Closes #177