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-import/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "kvitt-import"
+description = "Splitwise CSV importer for Kvitt (SPEC §10.8). Stub until milestone M9."
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+kvitt-domain = { version = "0.1.0", path = "../kvitt-domain" }
+kvitt-server = { version = "0.1.0", path = "../kvitt-server" }