fix(ui): bring the page title up to the logo

[joszz]

Follow-up to #448, which lined the sidebar logo up with the page title by moving the logo down to the title. That put both 48px from the top and pushed the whole page down.

Now the title comes up to the logo instead: both share a line 20px down, where the logo has always been, and the page content moves up with them.

• New --title-top token: the main column's top padding and the sidebar's top padding. It's 0.25rem beside the sidebar. On phones it stays at the 0.75rem topbar gutter, so phones don't change.
• The sides and bottom of the main column keep --content-padding.

Test plan

• Measured in Playwright on all six views at 1440 and 820 px: the logo and title both sit 20px down (the logo was at 20.7px before fix(ui): line the sidebar logo up with the page title #448), and the first nav link starts 2px above the first card.
• At 390 px the title still starts 12px below the topbar, and the drawer logo is level with the topbar's.
• pnpm exec vitest run (860 tests) and stylelint pass.

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