fix: clarify claim reward payment status

[Siesta0217]

Summary

• Derive the public claim status from sponsor payment progress instead of showing only the claim approval state.
• Show approved/unpaid claims as "Awaiting sponsor reward" and fully paid claims as "Rewarded".
• Add copy clarifying that approved claims waiting on sponsor reward require no contributor-side action.
• Add LiveView coverage for pending and paid claim reward states.

Test Plan

• Added regression tests in test/algora_web/live/claim_live_test.exs
• mix test test/algora_web/live/claim_live_test.exs (not run locally: this environment does not have Elixir/Mix installed; command fails with mix: command not found)

Closes #262

[CLAassistant]

All committers have signed the CLA.

[MikeGarciaAGM]

Small edge case to consider: Enum.all?(sponsors, ...) returns true on an empty list, so if this page ever renders a claim with no sponsor rows, the label would incorrectly show Rewarded. If that state is impossible here, ignore; otherwise a tiny sponsors != [] guard or an explicit empty-sponsor fallback would keep the label honest. The new tests cover pending/paid, but not the empty-sponsor path.

[MikeGarciaAGM]

Validated the empty-sponsor edge case end to end. The claim page now renders the approved label when no sponsor rows exist, and the sponsor-reward hint stays hidden on that path. I also exercised the mount + render flow with a self-contained harness.