Remove provider-initiated checkpoints

[bkontur]

Summary

Resolves #306 as Option B — remove entirely: provider-initiated checkpoints were designed (#7) and implemented (#92) without review, and the rationale does not hold up — the uploading client is the sole data holder and can submit the checkpoint on-chain in the same session, a client that retains the providers' signed commitments can already enforce/challenge that state, and the provider-to-provider coordination overlaps what replica nodes do. #305 already pulled the design out of the review-gated docs; this PR deletes the implementation.

What is removed

Layer	Removed
pallet-storage-provider	Extrinsics 32–36 (provider_checkpoint, configure_checkpoint_window, report_missed_checkpoint, claim_checkpoint_rewards, fund_checkpoint_pool), storage (CheckpointConfigs, LastCheckpointWindow, CheckpointRewards, CheckpointPool), their 5 events and 9 errors, the window/leader helpers, the complete_deregister reward drain, and the matching benchmarks, weights and ~20 unit tests
storage-primitives	CheckpointProposal, CheckpointWindowConfig
Runtimes (local + paseo)	DefaultCheckpointInterval, DefaultCheckpointGrace, CheckpointReward, CheckpointMissPenalty + Config wiring
Provider node	checkpoint_coordinator.rs (whole module), /checkpoint/sign + /checkpoint/duty + /checkpoint/trigger endpoints, --enable-checkpoint-coordinator flag, CheckpointChainClient impl in subxt_client.rs, ProviderState::checkpoint_cmd_tx, and the coordinator/API/auth tests
JS/TS SDK	configureCheckpointWindow, fundCheckpointPool, submitProviderCheckpoint, claimCheckpointRewards, reportMissedCheckpoint, fetchCheckpointDuty, signCheckpointProposal; layer-1 getCheckpointDuty / triggerCheckpoint + CheckpointDuty type
UIs	Provider dashboard checkpoint config/pool/reward/overdue display; drive-ui + s3-ui checkpoint duty/trigger panels
Examples / tooling / CI	examples/papi/checkpoint-missed.ts + just papi-checkpoint-missed, e2e tests 5.4/5.5/5.7, the coordinator flag in just start-provider and 4 CI workflow jobs
Docs	The five extrinsic entries + workflow + error rows in EXTRINSICS_REFERENCE.md, the runtime params in CLAUDE.md, mentions in the smart-contracts draft

Not touched: the client-initiated checkpoint / extend_checkpoint / challenge_checkpoint extrinsics, the /checkpoint-signature endpoint, and everything reading bucket.snapshot (e.g. the UIs' checkpoint-info displays) — that mechanism is canonical and unrelated.

Archive

The design and the full removed implementation (verbatim) are archived in docs/drafts/provider-initiated-checkpoints.md: pallet code, primitives, coordinator, HTTP handlers, chain-client impl, SDK wrappers, UI surfaces, the deleted example, and a behavior table for every removed test — enough to re-implement without archaeology if a validated rationale ever emerges.

Regenerated artifacts

Both runtime wasms were rebuilt and the metadata re-dumped, so:

• crates/storage-subxt: storage_paseo_runtime.scale + regenerated bindings (just subxt-codegen pipeline). The diff also picks up runtime-API drift the stale bindings were missing (current_anchor_block, anchor_block_time_millis).
• packages/papi/.papi/metadata/parachain.scale: descriptors regenerate from it on pnpm install.

Follow-up

• See Triage: remove (or justify) provider-initiated checkpoints #306 — if this capability is ever wanted again, the design needs to be re-evaluated first; the archived draft's rationale was never validated.