💄 Polish program cards and navigation

[flowerthrower]

Summary

• Open the full program directly from the landing page Program menu.
• Keep portraits and headings stationary when speaker and pitch cards expand.
• Let cards fit their content with equal top and bottom padding; remove trailing text margins.
• Move mobile portraits and text 8px left while keeping the timeline clear of break text.
• Place minutes on the heading row of every mobile card, with speaker fold arrows immediately before the minutes.
• Show Elie Gouzien (Alice & Bob) without a talk title.
• Update the existing focused checks and stylesheet cache version. No dependencies or workflow changes.

Validation

• node backend/check-calendar.mjs
• node backend/check-site-build.mjs
• git diff --check
• Local browser: all 16 expandable cards retain portrait and heading positions on desktop and mobile; all 22 mobile card durations align with headings at 375px and 320px without horizontal overflow.
• All 22 cards have matching 16px top and bottom padding on desktop and mobile (17px measured including the border).

Draft only; production remains unchanged until merge.

[github-actions]

Preview removed because this PR is closed.