Make admin storage pricing region-aware and sortable

[benben]

Summary

• select the storage customer-pricing schedule from the control plane's effective AWS region and remove the manual region switch
• make every storage-economics column sortable, including gross margin
• add per-organization and total prices needed to reach an 80% storage gross margin
• document region selection, pricing behavior, local setup, and failure recovery

Pricing model

The 80%-margin what-if price is calculated from the unrounded allocated AWS cost:

target price = allocated cost / (1 - 0.80) = 5 * allocated cost

Tests

• just ui-test
• GOFLAGS=-run=TestMonthlyUsageReportsDeploymentPricingRegion just test-controlplane-k8s
• just lint (currently reaches six pre-existing Staticcheck SA5011 findings in unrelated test files)

[github-actions]

Test Impact Plan

Deterministic summary of how this PR changes tests, CI runners, and coverage-risk signals.

Summary

Area	Added	Changed	Deleted
Test files	0	1	0
E2E/journey files	0	0	0
Workflow files	0	0	0

Signals

• Test cases: +1 / -0
• Assertions: +2 / -0
• Skips or known failures added: 0
• Workflow continue-on-error added: 0
• Workflow path filters added: 0
• Test commands removed from justfile: 0
• E2E/journey retry lines added: 0

Coverage risk: neutral or increased

No coverage-reduction warnings detected.