Rename Shoulder Allocations to Block Allocations

[smagala]

Epic: #31

Description

Use "Block Allocation(s)" consistently instead of "Shoulder Allocation(s)" for user-facing labels.

Changes

• client/src/pages/Allocations.tsx: Page title "Shoulder Allocations" -> "Block Allocations"
• client/src/components/Layout/Layout.tsx: Nav item "Allocations" -> "Block Allocations"
• client/src/pages/Dashboard.tsx: Section heading "Shoulder Allocation" -> "Block Allocation"

Estimate

1 story point