Fix mobile breakage site-wide and add a persistent, denser admin nav

[AlaqmarG]

Description

• Fixes site-wide mobile breakage: team page photo tiles are now a 2+ up grid on phones instead of one full-screen photo per person, plus a home-page hero/badge overflow fix and several other small breakage fixes found in the audit.
• Admin gets a persistent section nav instead of the tile grid being the only way to switch sections: a left rail on tablet/desktop (icon-only until 1024px, icons+labels above it), a fixed bottom tab bar on phones (Home, 2 pinned sections, a "More" button opening the existing Cmd+K palette).
• Admin panels, cards and list rows are visually tighter (smaller radius, lighter shadow, less padding) via the shared Panel component, so admin reads as a denser tool rather than a marketing page.
• Mail's own 3-pane layout is retuned to a lg breakpoint so it doesn't fight the new rail for space on tablets; a real bug this caused (message list squashed to ~0px width) is fixed.
• Nav correctly highlights only the single most-specific matching section, and both nav surfaces carry aria-current.

Public site's bold visual identity (color, borders, hard shadows) is untouched — this is about fixing breakage and density, not a redesign.

Checklist

• npm run typecheck, npm run lint, npm run format:check and npm run build pass
• Schema changes have a committed migration (npm run db:generate) — none
• New env vars added to .env.example, .env.local.example, deploy/docker-compose.yml and komodo/deploy-context.mjs — none
• Admin-only routes gated with requireAdmin / requireApprover — nav gating unchanged (same SECTIONS flags)
• Tested on the branch's preview deploy (light theme): real device-width headless screenshots across 9 sizes x 6 public pages (see below), plus the public-page regressions the review caught
• No secrets, internal hostnames or IPs committed

Testing Evidence

Team page, iPhone 14 (390px) — before	after: 2-up grid

CS Guide at 1024px — before (text clipped mid-line)	after

• The 1024px CS Guide overflow was a real bug this PR's own review pass missed — caught by re-auditing the deployed preview with real device emulation afterward, fixed in a follow-up commit (min-w-0 on the content column, the standard fix for a flex child that won't shrink below its content's natural width), and reconfirmed clean across all 9 sizes.
• Admin nav (rail, tab bar, mail's retuned breakpoint, density pass) needs a sign-in to click through on the preview; covered by the workflow's own review lenses and this session's independent typecheck/lint/knip/build pass instead.