Bring the miner-ui and extension under a coverage gate

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Problem: Both apps/gittensory-miner-ui and apps/gittensory-miner-extension are excluded from Codecov via the blanket apps/** ignore.

Area: AMS / Testing

Proposal: Carve out an explicit inclusion for these two apps' meaningful source (excluding generated/build output), and establish a coverage baseline.

Deliverables:

• Both apps under real coverage measurement where technically feasible.

Boundaries:

• The extension's test instrumentation may need adjustment first (see the CI-wiring issue below) before coverage attribution works correctly.

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JSO-3525