[MCP] Emit progress notifications for long-running tools

[manoahLinks]

Summary

mindvault_buy and mindvault_register_onchain can take many seconds across sponsored-account funding, x402 payment, and Soroban submission, with no feedback until they finish.

Scope

• Keep the implementation aligned with the existing MindVault architecture.
• Add or update automated tests.
• Update docs when the change affects contributors, deployers, or agent users.

Acceptance criteria

• When the client supplies a progress token, both tools emit progress notifications at each phase boundary.
• Behaviour is unchanged when no progress token is supplied, and tests cover both paths.
• Failure cases are deterministic and safe to show in issue-driven contributor work.
• Relevant local tests pass.

[Stephan-Thomas]

@Stephan-Thomas has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

hi, i would like to work on this.

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[ABEEGOLD]

@ABEEGOLD has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue because i can do it.

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[Adotse10066]

@Adotse10066 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi Maintainer, I'd love to work on this issue please. I deliver high impact solutions, ensuring seamless workflow and client satisfaction

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[opeolarewaju5-glitch]

@opeolarewaju5-glitch has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello maintainer, I can fix this issue

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[Hunterly01]

@Hunterly01 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would love to work on this issue professionally, please assign it to me

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[Michael997glitch]

@Michael997glitch has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I’ve resolved similar problems in the past and am confident I can implement a clean, efficient fix quickly,if am given the opportunity.

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