refactor(request): delegate payment sessions to mppx

[gakonst]

Summary

• delegate Tempo session bootstrap, recovery, voucher accounting, top-ups, and receipts to tempo.session.manager
• use MPPx's Node SQLite ChannelStore, defaulting to the shared ~/.tempo/wallet/channels.db
• preserve wallet-cli's existing access-key/private-key/provider identity resolution and HTTP retry/redirect/proxy behavior
• remove 590 lines of duplicate session state-machine code from the request command

Depends on the client rehydration API in wevm/mppx#675 and the independent Node SQLite store in wevm/mppx#677. Until those changes are released together, the dependency is pinned to immutable pkg.pr.new commit 8b64593, which contains both runtime changes (plus the server-side follow-up from #676).

Current-main red proof

Tested against exact origin/main commit f758ec2 in a detached worktree with the identical regression test:

FAIL uses managed session bootstrap before retrying a Tempo session challenge
IncurError: Session payment exceeds --max-spend

Observed request sequence on current main: GET only. The legacy wallet-owned path tried to calculate/open a deposit and never sent the bootstrap request.

Feature green proof

The identical test passes here with request sequence GET -> HEAD -> GET: the initial 402 selects the managed path, MPPx bootstraps the session, and wallet-cli retries the content request.

The preview was installed from the pinned lockfile into a clean dependency graph before the latest validation run; mppx/client/node resolved from commit 8b64593.

Validation:

• focused request suite: 22 tests passed
• application and test TypeScript projects: pass
• format check: pass
• prior full Vitest run: 8 files, 117 tests passed
• prior changelog validation: pass
• prior tempo-request bundle and native package checks: pass; bundled output retains node:sqlite