feat: complete TUI Phase 0 — Toolchain Gate

Implements the full lore-tui crate scaffold with 6 Phase 0 modules:

- message.rs: Msg (~40 variants), Screen (12), EntityKey, AppError, InputMode
- clock.rs: Clock trait with SystemClock + FakeClock for deterministic testing
- safety.rs: Terminal sanitizer (ANSI filter), URL policy, PII/secret redaction
- db.rs: DbManager with 3 reader pool (round-robin) + dedicated writer (WAL mode)
- theme.rs: Flexoki adaptive theme (19 slots), state/event colors, label styling
- app.rs: Minimal LoreApp Model trait impl proving FrankenTUI integration

68 tests, clippy clean, fmt clean. Closes bd-3ddw, bd-c9gk, bd-2lg6,
bd-3ir1, bd-2kop, bd-5ofk, bd-2emv, bd-1cj0.

crates/lore-tui/src/app.rs

@@ -0,0 +1,101 @@
+#![allow(dead_code)] // Phase 0: minimal scaffold, fleshed out in bd-6pmy
+
+//! Minimal FrankenTUI Model implementation for the lore TUI.
+//!
+//! This is the Phase 0 integration proof — validates that the ftui Model trait
+//! compiles with our Msg type and produces basic output. The full LoreApp with
+//! screen routing, navigation stack, and action dispatch comes in bd-6pmy.
+
+use ftui::{Cmd, Frame, Model};
+
+use crate::message::Msg;
+
+// ---------------------------------------------------------------------------
+// LoreApp
+// ---------------------------------------------------------------------------
+
+/// Root model for the lore TUI.
+///
+/// Phase 0: minimal scaffold that renders a placeholder and handles Quit.
+/// Phase 1 (bd-6pmy) will add screen routing, DbManager, theme, and subscriptions.
+pub struct LoreApp;
+
+impl Model for LoreApp {
+    type Message = Msg;
+
+    fn init(&mut self) -> Cmd<Self::Message> {
+        Cmd::none()
+    }
+
+    fn update(&mut self, msg: Self::Message) -> Cmd<Self::Message> {
+        match msg {
+            Msg::Quit => Cmd::quit(),
+            _ => Cmd::none(),
+        }
+    }
+
+    fn view(&self, _frame: &mut Frame) {
+        // Phase 0: no-op view. Phase 1 will render screens via the frame.
+    }
+}
+
+/// Verify that `App::fullscreen(LoreApp).run()` compiles.
+///
+/// This is a compile-time check — we don't actually run it because that
+/// would require a real TTY. The function exists solely to prove the wiring.
+#[cfg(test)]
+fn _assert_app_fullscreen_compiles() {
+    // This function is never called — it only needs to compile.
+    fn _inner() {
+        use ftui::App;
+        let _app_builder = App::fullscreen(LoreApp);
+        // _app_builder.run() would need a TTY, so we don't call it.
+    }
+}
+
+/// Verify that `App::inline(LoreApp, 12).run()` compiles.
+#[cfg(test)]
+fn _assert_app_inline_compiles() {
+    fn _inner() {
+        use ftui::App;
+        let _app_builder = App::inline(LoreApp, 12);
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_lore_app_init_returns_none() {
+        let mut app = LoreApp;
+        let cmd = app.init();
+        assert!(matches!(cmd, Cmd::None));
+    }
+
+    #[test]
+    fn test_lore_app_quit_returns_quit_cmd() {
+        let mut app = LoreApp;
+        let cmd = app.update(Msg::Quit);
+        assert!(matches!(cmd, Cmd::Quit));
+    }
+
+    #[test]
+    fn test_lore_app_tick_returns_none() {
+        let mut app = LoreApp;
+        let cmd = app.update(Msg::Tick);
+        assert!(matches!(cmd, Cmd::None));
+    }
+
+    #[test]
+    fn test_lore_app_navigate_returns_none() {
+        use crate::message::Screen;
+        let mut app = LoreApp;
+        let cmd = app.update(Msg::NavigateTo(Screen::Dashboard));
+        assert!(matches!(cmd, Cmd::None));
+    }
+}