M2a: server workspace, kvitt-domain, skeleton routes, OpenAPI match, Dockerfile

Cargo workspace (kvitt-domain, kvitt-server, kvitt-import), Rust 1.99.1 pinned.
kvitt-domain passes every Rust vector and adds next_occurrence_date (D-015).
kvitt-server: config, SQLite pool (WAL, §8.9 pragmas), migration 0001 identical to
the contract schema, error type for all 25 codes, auth extractor and protocol
layer, all 33 routes (E-1/E-2 implemented, the rest 501), utoipa document equal
to contracts/openapi.yaml, seams for M3/M4/M9, serve/migrate/healthcheck.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/crates/kvitt-server/src/main.rs

@@ -0,0 +1,50 @@
+//! `kvitt-server`: parses the subcommand, sets up JSON logging and the runtime (2 worker threads, SPEC §6.3), and
+//! runs it.
+
+// No unwrap/expect outside tests (CLAUDE.md server rule); integration tests are separate crates and may use them.
+#![cfg_attr(not(test), deny(clippy::unwrap_used, clippy::expect_used))]
+
+use std::process::ExitCode;
+
+use clap::Parser;
+use kvitt_server::cli::{self, Cli};
+use kvitt_server::config::{Config, DEFAULT_LOG_FILTER};
+use tracing_subscriber::EnvFilter;
+
+/// Worker threads of the tokio runtime (SPEC §6.3).
+const WORKER_THREADS: usize = 2;
+
+fn main() -> ExitCode {
+    let cli = Cli::parse();
+
+    let filter =
+        EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(DEFAULT_LOG_FILTER));
+    tracing_subscriber::fmt()
+        .json()
+        .with_env_filter(filter)
+        .with_current_span(true)
+        .with_span_list(false)
+        .with_writer(std::io::stdout)
+        .init();
+
+    let config = match Config::from_env() {
+        Ok(config) => config,
+        Err(error) => {
+            eprintln!("configuration: {}", error.message);
+            return ExitCode::FAILURE;
+        }
+    };
+
+    let runtime = match tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(WORKER_THREADS)
+        .enable_all()
+        .build()
+    {
+        Ok(runtime) => runtime,
+        Err(error) => {
+            eprintln!("cannot start the runtime: {error}");
+            return ExitCode::FAILURE;
+        }
+    };
+    runtime.block_on(cli::run(cli.command, config))
+}