fix(payments): harden client payment attempts and retries

[1amKhush]

Closes #107

Summary

Repeated offers and delayed callbacks could repeat wallet work or retry completed requests.

• Validate payment offers, options, and configuration before wallet callbacks.
• Retain payment-attempt outcomes and add per-invocation amount, attempt, and deadline limits.
• Cancel retries and fence callbacks on completion, cancellation, or close.
• Preserve request identity and enforce deliverable Nostr retries.
• Add regression coverage for request generations and both encryption modes.

Validation

• Full concurrent suite: 693 passed, 5 live-wallet tests skipped, 0 failures.
• Typecheck, lint, build, and export checks passed.
• 100 focused tests passed; 19 regression cases reproduced failures on the original baseline.

Notes

• Amount limits apply to advertised amounts; wallet handlers must verify payment payloads.
• Attempt history is bounded and refuses new payments at capacity.
• Full browser bundling encounters a pre-existing applesauce-relay resolution error; helper bundles and the wrapper with that dependency externalized passed.

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