fix(#326): add role-based auth and daily spending limits to institutional wallet

[danieloche635-bit]

Summary

Implements role-based authorization and daily spending limits for the institutional-grade multisig wallet, completing the remaining acceptance criteria for issue #326.

Changes

New Features

• WalletRole enum (Admin, Approver, Executor, Viewer) with role-based access control
• DailySpendingLimit per-asset spending cap configuration
• Role enforcement in propose(), approve(), and execute() entrypoints
• Spending limit enforcement in execute() using the new Transaction.spend_amount and Transaction.spend_asset fields

New Entrypoints

• assign_role(addr, role) - Assign a role to an address (admin only, via multisig)
• revoke_role(addr) - Remove a role assignment
• set_daily_spending_limit(asset, daily_limit) - Set per-asset daily spending cap
• set_default_spending_limit(daily_limit) - Set default spending cap for all assets
• get_role(addr), get_daily_spending_limit(asset), get_default_spending_limit() - View functions

Bug Fix

• Fixed test.rs: added missing Symbol import for Symbol::new usage in recovery tests
• Updated Transaction struct with spend_amount and spend_asset optional fields

Files Changed

• stellar-lend/contracts/institutional-wallet/src/types.rs - Added WalletRole, DailySpendingLimit, new errors, Transaction fields
• stellar-lend/contracts/institutional-wallet/src/storage.rs - Added role limit storage functions
• stellar-lend/contracts/institutional-wallet/src/lib.rs - Role limit entrypoints
• stellar-lend/contracts/institutional-wallet/src/test.rs - Fixed Symbol import

[vercel]

@danieloche635-bit is attempting to deploy a commit to the smartdevs17's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

Hey @danieloche635-bit! 👋 It looks like this PR isn't linked to any issue.

If this PR is for one of the issues assigned to you as part of a Wave, please link it to ensure your contribution is tracked properly. You can do this by adding a keyword to the PR description (e.g., Closes #123), or by clicking a button below:

Issue	Title
#327	Add rebalancing engine for autonomous portfolio management	Link to this issue
#328	Implement commitment-based lending with forward rate agreements	Link to this issue
#326	Build institutional-grade multisig wallet with spending limits	Link to this issue

ℹ️ Learn more about linking PRs to issues