Rework dashboard with actionable content

[olsonjp]

Changes needed

• Replace the welcome message with an actionable summary showing: active samples count, storage usage %, alerts
• Drop centered "Welcome to Krill" and "Laboratory Information Management System" subtitle
• Make every stat card a link to a pre-filtered view of the relevant list
• Improve Recent Activity entries to read like: "talia.hoang created aliquot 134L/A #20892 in Sikora LN2 Initial commit #1 / Box 04"
• Remove "Settings" from Quick Actions (keep "New Aliquot" and "Find Aliquot" as primaries)
• Fill empty space with: in-progress work, freezer fill warnings, recent team activity in detail
• Cap content width around 1500–1600px and center

Priority

P0