Feat: mentorship, skill verification, charity split & tax strategies (#884, #885, #886, #887)

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["contracts/split", "contracts/dashboard", "contracts/invoice-escrow", "contracts/factory", "contracts/registry"]
+members = ["contracts/split", "contracts/dashboard", "contracts/invoice-escrow", "contracts/factory", "contracts/registry", "contracts/mentorship", "contracts/skill-verification", "contracts/charity-split", "contracts/tax-strategy"]
 resolver = "2"
 
 [workspace.dependencies]

contracts/charity-split/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "charity-split"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+soroban-sdk = { workspace = true }
+
+[dev-dependencies]
+soroban-sdk = { workspace = true, features = ["testutils"] }
+
+[features]
+testutils = ["soroban-sdk/testutils"]

contracts/charity-split/src/errors.rs

@@ -0,0 +1,47 @@
+//! Error variants for the charity-split contract.
+//!
+//! Discriminants are stable — never reorder, only append.
+
+use soroban_sdk::contracterror;
+
+#[contracterror]
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[repr(u32)]
+pub enum Error {
+    /// Contract has already been initialized.
+    AlreadyInitialized = 1,
+    /// Contract has not been initialized yet.
+    NotInitialized = 2,
+    /// Caller is not the contract admin.
+    NotAdmin = 3,
+    /// The charity is already registered.
+    CharityAlreadyRegistered = 4,
+    /// No charity is registered at this address.
+    CharityNotFound = 5,
+    /// The charity has been deactivated by the admin.
+    CharityInactive = 6,
+    /// Donation share must be between `MIN_DONATION_BPS` and `MAX_DONATION_BPS`.
+    InvalidDonationBps = 7,
+    /// Recipient and amount lists are empty, mismatched or too long.
+    InvalidRecipients = 8,
+    /// Amount must be strictly positive.
+    InvalidAmount = 9,
+    /// Recipient amounts do not sum to the invoice total.
+    TotalMismatch = 10,
+    /// Invoice ID was not found in storage.
+    InvoiceNotFound = 11,
+    /// The invoice is not open for this operation.
+    InvoiceNotOpen = 12,
+    /// The payment would exceed the invoice total.
+    OverFunded = 13,
+    /// Caller is not the invoice creator.
+    NotCreator = 14,
+    /// The invoice is not cancelled, so refunds are unavailable.
+    NotCancelled = 15,
+    /// The payer has nothing to refund.
+    NothingToRefund = 16,
+    /// The charity cannot also be a split recipient.
+    CharityIsRecipient = 17,
+    /// Arithmetic overflow.
+    Overflow = 18,
+}