fix(ui): line the sidebar logo up with the page title

[joszz]

On desktop and tablet the GarageStack logo sat at the very top of the sidebar, about 28px above the page title beside it, so the two headings looked out of line.

• The sidebar's top padding now follows the main column's padding, and the logo's row is as tall as the page title's line. The logo and every page title now sit at the same height, on every breakpoint.
• The gap under the logo matches the one under the page header, so the first nav link starts level with the first card.
• The shared values live in two new tokens, --content-padding and --page-title-height. The phone and tablet breakpoints now set the padding through the token.
• On phones, the drawer's logo opens at the same height as the top bar's.

Test plan

• Measured in Playwright on all six views at 1920, 1440, 1024, 820 and 768 px: the logo's middle matches the title's (48 px desktop, 40 px tablet), and the first nav link starts within 2 px of the first card.
• At 390 px the drawer logo sits at 28 px, against 27.5 px for the top bar's.
• pnpm exec vitest run (860 tests) and stylelint pass.

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