feat(maestro): add [tui] config section + crossterm workspace dep (NAP-277)

Schema-only — adds `TuiSection` with `leader`, `chord_timeout_ms`, and per-mode
keymap override maps; pulls crossterm into the workspace deps so the next
commit's input layer can consume it.

Field set matches `docs/superpowers/specs/2026-05-28-maestro-tui-design.md` §3.9.

crates/maestro-config/src/lib.rs

@@ -27,6 +27,7 @@
 //! URL derivation helper. Each binary applies its own env-var precedence and
 //! defaults on top of [`MaestroConfigFile`].
 
+use std::collections::BTreeMap;
 use std::net::SocketAddr;
 use std::path::{Path, PathBuf};
 
@@ -76,6 +77,8 @@ pub struct MaestroConfigFile {
     pub registry: RegistrySection,
     #[serde(default, skip_serializing_if = "WebSection::is_empty")]
     pub web: WebSection,
+    #[serde(default, skip_serializing_if = "TuiSection::is_empty")]
+    pub tui: TuiSection,
 }
 
 /// Fields consumed by more than one binary (CLI + daemon, daemon + registry).
@@ -228,6 +231,38 @@ impl WebSection {
     }
 }
 
+/// `[tui]` — `maestro tui` settings (NAP-275 epic, phase 2 NAP-277).
+///
+/// Leader key, chord timeout, and per-mode keymap overrides. The TUI ships
+/// with a default keymap; entries in `keymap_normal` / `keymap_insert` are
+/// applied **over** the defaults, so a partial override is enough.
+#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub struct TuiSection {
+    /// Canonical key form, e.g. `"ctrl-a"`. Default `ctrl-a`.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub leader: Option<String>,
+    /// Maximum interval between chord keys before a held prefix is dropped.
+    /// Default `1000`.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub chord_timeout_ms: Option<u64>,
+    /// Normal-mode bindings: canonical input → action string. Applied over
+    /// the shipped defaults.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub keymap_normal: BTreeMap<String, String>,
+    /// Insert-mode bindings, same semantics as `keymap_normal`.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub keymap_insert: BTreeMap<String, String>,
+}
+
+impl TuiSection {
+    pub fn is_empty(&self) -> bool {
+        self.leader.is_none()
+            && self.chord_timeout_ms.is_none()
+            && self.keymap_normal.is_empty()
+            && self.keymap_insert.is_empty()
+    }
+}
+
 impl MaestroConfigFile {
     /// Strict load — error with [`ConfigError::MissingFile`] if absent.
     pub fn load(path: &Path) -> Result<Self, ConfigError> {

crates/maestro-tui/Cargo.toml

@@ -9,4 +9,6 @@ description = "Terminal UI client over the local maestro daemon's `/api/*` surfa
 
 [dependencies]
 clap.workspace = true
+crossterm.workspace = true
+maestro-config.workspace = true
 thiserror.workspace = true