workspace: scaffold Cargo workspace with rpn-core and rpn-cli

First code in the repo. Workspace root is Application/ per readme;
members are src/core (crate rpn-core) and src/cli (binary rpnc).
Crate names are prefixed to avoid clashing with the std `core`
crate; directory names follow the readme layout.

Dependencies (versions pinned in Cargo.lock):
- core: sqlx (mysql, runtime-tokio, chrono, rust_decimal), chrono,
  csv, thiserror, serde/serde_json, tracing, plus sha2 (SHA-256
  file checksums required by schema.sql), rust_decimal (exact
  DECIMAL(10,2) money, forced by the "money is DECIMAL
  everywhere" decision), tokio and tempfile as dev deps.
- cli: clap (derive), tokio, tracing-subscriber (env-filter),
  anyhow, serde/serde_json, chrono, csv.

The extra crates beyond the readme stack (sha2, rust_decimal,
tracing-subscriber, tempfile-dev) are direct consequences of
already-committed decisions; flag for maintainer review.

No feature logic yet: rpnc is an empty shell, the domain modules
land in the TDD slices that follow.

Application/Cargo.toml

@@ -0,0 +1,7 @@
+[workspace]
+resolver = "3"
+members = ["src/core", "src/cli"]
+
+[workspace.package]
+edition = "2024"
+rust-version = "1.85"

Application/src/cli/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "rpn-cli"
+version = "0.1.0"
+publish = false
+edition.workspace = true
+rust-version.workspace = true
+
+[[bin]]
+name = "rpnc"
+path = "src/main.rs"
+
+[dependencies]
+anyhow = "1.0.104"
+chrono = "0.4.45"
+clap = { version = "4.6.6", features = ["derive"] }
+csv = "1.4.0"
+rpn-core = { path = "../core" }
+serde = { version = "1.0.229", features = ["derive"] }
+serde_json = "1.0.151"
+tokio = { version = "1.53.1", features = ["macros", "rt-multi-thread"] }
+tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }

Application/src/cli/src/main.rs

@@ -0,0 +1 @@
+fn main() {}

Application/src/core/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "rpn-core"
+version = "0.1.0"
+publish = false
+edition.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+chrono = "0.4.45"
+csv = "1.4.0"
+rust_decimal = "1.43.0"
+serde = { version = "1.0.229", features = ["derive"] }
+serde_json = "1.0.151"
+sha2 = "0.11.0"
+sqlx = { version = "0.8.6", features = ["mysql", "runtime-tokio", "chrono", "rust_decimal"] }
+thiserror = "2.0.20"
+tracing = "0.1.44"
+
+[dev-dependencies]
+tempfile = "3.27.0"
+tokio = { version = "1.53.1", features = ["macros", "rt-multi-thread"] }

Application/src/core/src/lib.rs

@@ -0,0 +1 @@
+//! Domain logic for RustyRPN: ingest, invoices, Fortnox, car registry.