style(landing): hero spacing rework into title+tagline and dial+grid groups

[e35ventura]

Follow-up polish to #1363: these two commits were pushed to the old branch after it merged, so they never landed in test.

What changed

Hero spacing reworked from three floating strata into two visual groups:

• Title + tagline read as one header unit: the tagline moved above the timeline dial, sits 8px under the title, and its letter-spacing dropped from 0.16em to 0.08em (with a slightly larger 0.7rem size) so it reads as a quiet caption instead of a banner competing with the title's width.
• Dial + grid read as control plus content: the dial now sits just above the grid it switches, so it registers as the grid's tab bar instead of an orphaned element mid-hero.
• The duplicate dashboard-side tagline was consolidated into the single line under the title (it still swaps copy with the dial state).
• Page top padding reduced so the first row of cards starts on-screen.

Verification

• tsc -b clean; eslint + prettier via lint-staged on commit.
• Verified in Chromium at 1440px: title/tagline gap 8px, tagline/dial ~40px, dial/grid 24px.