feat(request): plan every charge through machine-fetch (stack 3/6)

[brendanjryan]

3/6 — Phase 1. Every charge is planned through machine-fetch before signing (src/payment/funding.ts: mppxRequirement → planPayment → extension().preparePayment), and the credential is created with the context funding prepared. --max-spend becomes maxPayment as an asset list of the USD tokens the CLI lists. Behavior change: a charge in an unlisted token is refused with E_LIMIT_EXCEEDED instead of being compared as if it had six decimals. machine-fetch error codes map to CLI codes and ctas. TEMPO_DEV_CHAINS adds development tokens (used by the e2e harness).

Paired PRs

• machine-fetch (merged): MF-17 https://github.com/tempoxyz/machine-fetch/pull/66 · MF-18 https://github.com/tempoxyz/machine-fetch/pull/67
• mppx (merged on main): mppx-1 auto-swap allowlist and OUSD default feat(tempo): auto-swap allowlist (autoSwap.fallback) and OUSD in the default currencies wevm/mppx#1054 · mppx-3 auto-swap reads without the account fix(tempo): read auto-swap balances and quotes without the account wevm/mppx#1055
• wallet-cli stack: 1 build: vendor mppx and machine-fetch (machine-fetch stack 1/6) #274 · 2 test(e2e): local Docker harness (machine-fetch stack 2/6) #275 · 3 feat(request): plan every charge through machine-fetch (stack 3/6) #276 · 4 feat(request): Tempo DEX funding from OUSD (stack 4/6) #277 · 5 feat(request): EVM and x402 offers from a remote payer (stack 5/6) #278 · 6 feat(request): cross-chain funding through Relay (stack 6/6) #279

wallet-cli vendors machine-fetch main @ d168943 (0.3.0) and mppx brendan/wallet-cli-needs @ 8295134 (mppx@0.12.0 + the commits merged upstream as 82810df and 0acc2bc), pinned by commit until we choose to upgrade.