Make project navigation and evidence scrolling persistent

[jonashertner]

What changed

• replace the hidden mobile Info menu with persistent, plainly named project navigation at every breakpoint
• make the entire evidence column one continuous, visible, keyboard-focusable scroll surface
• keep the layer rail available while evidence scrolls and prevent long German labels from colliding in the narrow desktop rail
• separate navigation from language/theme utilities on reading pages and preserve deep-link alignment
• tighten mobile timeline proportions without obscuring the map
• add release contracts that prevent hidden project links or a fragmented scroller from returning

Verification

• npm run release
• npm run check:links (81 checked, 0 dead)
• git diff --check
• Chrome: 320x568, 390x844, 768x1024, 844x390, 1024x768, and 1440x900
• Chrome: map, project brief, selected detail panel, reservoir timeline, Method, and About#collaborate