refactor: DDD/CQRS architecture, unified crate layout

- crates: common→application, api→presentation, infrastructure/*→adapters/*
- new crates: api-types, infra-wiring
- domain: errors/, models/, value_objects/, ports/, services/
- application: CQRS use cases (songs/, tabs/) w/ commands, queries, deps
- unified DomainError replaces RepositoryError
- workspace deps, unused dep cleanup
- fix: parse plain-text chord lines (UG drops spans mid-song)
- tests extracted to separate modules (tests/ dirs)

crates/application/.gitignore

@@ -0,0 +1 @@
+Cargo.lock

crates/application/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "application"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+uuid = { workspace = true }
+domain = { workspace = true }

crates/application/src/lib.rs

@@ -0,0 +1,2 @@
+pub mod songs;
+pub mod tabs;

crates/application/src/songs/commands.rs

@@ -0,0 +1,17 @@
+use domain::models::Song;
+use uuid::Uuid;
+
+pub struct SaveSongCommand {
+    pub song: Song,
+}
+
+pub struct DeleteSongCommand {
+    pub id: Uuid,
+}
+
+pub struct UpdateSongMetaCommand {
+    pub id: Uuid,
+    pub title: Option<String>,
+    pub artist: Option<String>,
+    pub original_key: Option<String>,
+}

crates/application/src/songs/delete_song.rs

@@ -0,0 +1,8 @@
+use domain::errors::DomainError;
+
+use super::commands::DeleteSongCommand;
+use super::deps::SongCommandDeps;
+
+pub async fn execute(deps: &SongCommandDeps, cmd: DeleteSongCommand) -> Result<(), DomainError> {
+    deps.repo.delete(cmd.id).await
+}

crates/application/src/songs/deps.rs

@@ -0,0 +1,11 @@
+use domain::ports::{SongRepositoryPort, SongSearchPort};
+use std::sync::Arc;
+
+pub struct SongCommandDeps {
+    pub repo: Arc<dyn SongRepositoryPort>,
+}
+
+pub struct SongQueryDeps {
+    pub repo: Arc<dyn SongRepositoryPort>,
+    pub search: Arc<dyn SongSearchPort>,
+}

crates/application/src/songs/get_song.rs

@@ -0,0 +1,12 @@
+use domain::errors::DomainError;
+use domain::models::Song;
+
+use super::deps::SongQueryDeps;
+use super::queries::GetSongQuery;
+
+pub async fn execute(
+    deps: &SongQueryDeps,
+    query: GetSongQuery,
+) -> Result<Option<Song>, DomainError> {
+    deps.repo.get(query.id).await
+}

crates/application/src/songs/list_songs.rs

@@ -0,0 +1,12 @@
+use domain::errors::DomainError;
+use domain::models::SongSummary;
+
+use super::deps::SongQueryDeps;
+use super::queries::ListSongsQuery;
+
+pub async fn execute(
+    deps: &SongQueryDeps,
+    query: ListSongsQuery,
+) -> Result<Vec<SongSummary>, DomainError> {
+    deps.repo.list(query.sort, query.order).await
+}

crates/application/src/songs/mod.rs

@@ -0,0 +1,9 @@
+pub mod commands;
+pub mod delete_song;
+pub mod deps;
+pub mod get_song;
+pub mod list_songs;
+pub mod queries;
+pub mod save_song;
+pub mod search_songs;
+pub mod update_meta;

crates/application/src/songs/queries.rs

@@ -0,0 +1,17 @@
+use domain::value_objects::{SortField, SortOrder};
+use uuid::Uuid;
+
+pub struct ListSongsQuery {
+    pub sort: SortField,
+    pub order: SortOrder,
+}
+
+pub struct GetSongQuery {
+    pub id: Uuid,
+}
+
+pub struct SearchSongsQuery {
+    pub query: String,
+    pub sort: SortField,
+    pub order: SortOrder,
+}

crates/application/src/songs/save_song.rs

@@ -0,0 +1,12 @@
+use domain::errors::DomainError;
+use domain::models::StoredSong;
+
+use super::commands::SaveSongCommand;
+use super::deps::SongCommandDeps;
+
+pub async fn execute(
+    deps: &SongCommandDeps,
+    cmd: SaveSongCommand,
+) -> Result<StoredSong, DomainError> {
+    deps.repo.save(&cmd.song).await
+}

crates/application/src/songs/search_songs.rs

@@ -0,0 +1,14 @@
+use domain::errors::DomainError;
+use domain::models::SongSummary;
+
+use super::deps::SongQueryDeps;
+use super::queries::SearchSongsQuery;
+
+pub async fn execute(
+    deps: &SongQueryDeps,
+    query: SearchSongsQuery,
+) -> Result<Vec<SongSummary>, DomainError> {
+    deps.search
+        .search(&query.query, query.sort, query.order)
+        .await
+}

crates/application/src/songs/update_meta.rs

@@ -0,0 +1,19 @@
+use domain::errors::DomainError;
+use domain::models::SongSummary;
+
+use super::commands::UpdateSongMetaCommand;
+use super::deps::SongCommandDeps;
+
+pub async fn execute(
+    deps: &SongCommandDeps,
+    cmd: UpdateSongMetaCommand,
+) -> Result<SongSummary, DomainError> {
+    deps.repo
+        .update_meta(
+            cmd.id,
+            cmd.title.as_deref(),
+            cmd.artist.as_deref(),
+            cmd.original_key.as_deref(),
+        )
+        .await
+}

crates/application/src/tabs/commands.rs

@@ -0,0 +1,4 @@
+pub struct ParseTabCommand {
+    pub source: Option<String>,
+    pub html: Option<String>,
+}

crates/application/src/tabs/deps.rs

@@ -0,0 +1,7 @@
+use domain::ports::{TabFetcherPort, TabParserPort};
+use std::sync::Arc;
+
+pub struct ParseTabDeps {
+    pub fetcher: Arc<dyn TabFetcherPort>,
+    pub parser: Arc<dyn TabParserPort>,
+}

crates/application/src/tabs/mod.rs

@@ -0,0 +1,3 @@
+pub mod commands;
+pub mod deps;
+pub mod parse_tab;

crates/application/src/tabs/parse_tab.rs

@@ -0,0 +1,33 @@
+use std::path::PathBuf;
+
+use domain::errors::DomainError;
+use domain::models::Song;
+use domain::ports::TabSource;
+
+use super::commands::ParseTabCommand;
+use super::deps::ParseTabDeps;
+
+pub async fn execute(deps: &ParseTabDeps, cmd: ParseTabCommand) -> Result<Song, DomainError> {
+    let html = if let Some(raw_html) = cmd.html {
+        Ok(raw_html)
+    } else if let Some(source) = cmd.source {
+        let tab_source = if source.starts_with("file://") {
+            let path = source.trim_start_matches("file://");
+            TabSource::File(PathBuf::from(path))
+        } else {
+            TabSource::Url(source)
+        };
+        deps.fetcher
+            .fetch(tab_source)
+            .await
+            .map_err(|e| DomainError::InfrastructureError(e.to_string()))
+    } else {
+        Err(DomainError::ValidationError(
+            "Provide either 'source' or 'html'".into(),
+        ))
+    }?;
+
+    deps.parser
+        .parse(&html)
+        .map_err(|e| DomainError::InfrastructureError(e.to_string()))
+}