phase 1 scaffold: cargo workspace + 3 crates + roadmap + architecture

Repo skeleton for aldabra, the rust-native cardano lite wallet
with MCP server interface. Builds end-to-end, types in place,
real cardano primitives land next pass.

Crates:
  wallet-core   — pure crypto + types. mnemonic, key derivation,
                  signing. No I/O. Security boundary.
  wallet-chain  — pluggable backends. ChainBackend trait, Koios
                  client (stub for now). Ogmios + submit in phase 2.
  wallet-mcp    — the binary. stdio MCP transport via rmcp.

Phase plan in ROADMAP.md, threat model in docs/architecture.md.

This is also Sulkta's first Rust project + a real-world workout for
ci-runner's rust toolchain.

Cargo.toml

@@ -0,0 +1,70 @@
+# Cargo workspace root for aldabra.
+#
+# Three crates:
+#   wallet-core   — key derivation, signing, types, mnemonic handling
+#   wallet-chain  — pluggable chain backends (Koios, Ogmios). Trait-first.
+#   wallet-mcp    — binary; the MCP server, glues core+chain together.
+#
+# Workspace deps are pinned here so all three crates use the same versions.
+# Add a dep here, then reference it in each crate's Cargo.toml as
+#   foo = { workspace = true }
+[workspace]
+resolver = "2"
+members = [
+    "crates/wallet-core",
+    "crates/wallet-chain",
+    "crates/wallet-mcp",
+]
+
+[workspace.package]
+version = "0.0.1"
+edition = "2021"
+license-file = "LICENSE"
+repository = "https://git.sulkta.com/Sulkta-Coop/aldabra"
+authors = ["Sulkta <oss@sulkta.com>"]
+
+[workspace.dependencies]
+# Async runtime — almost everything we do is I/O bound (chain queries, MCP stdio)
+tokio = { version = "1", features = ["full"] }
+
+# Cardano stack — pallas is the rust-native primitives library by txpipe.
+# We pull individual crates rather than the meta-crate so we control feature flags.
+pallas-primitives = "0.32"
+pallas-codec = "0.32"
+pallas-crypto = "0.32"
+pallas-addresses = "0.32"
+pallas-txbuilder = "0.32"
+pallas-network = "0.32"
+
+# Mnemonic + key derivation. bip39 for the wordlist, then pallas-crypto
+# handles the Cardano-specific CIP-3 / CIP-1852 derivation paths.
+bip39 = "2"
+
+# At-rest encryption for the mnemonic + derived keys on disk. age is
+# what the cauldron Fernet pattern would have been if we'd had it back
+# then — modern, audited, FOSS, and the secret never has to round-trip
+# through a daemon password prompt.
+age = "0.10"
+
+# Memory hygiene — wipe key material from RAM when keys go out of scope.
+zeroize = { version = "1", features = ["derive"] }
+
+# Errors — anyhow at the boundaries (binary), thiserror for crate-internal types
+anyhow = "1"
+thiserror = "1"
+
+# Serde for everything JSON
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+# HTTP client for Koios + future Ogmios HTTP endpoints
+reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }
+
+# MCP SDK for Rust. Note: the official Rust SDK has been moving fast
+# (modelcontextprotocol/rust-sdk on github). Pin a version once we
+# verify the API shape we actually use.
+rmcp = { version = "0.1", features = ["server", "transport-io"] }
+
+# Logging
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }