Refactor: untangle framework library from todo example

The codebase is now split into two clear layers:

Framework library (src/):
- lib.rs — public API surface, re-exports all framework types
- signal.rs — SignalOpts, Signal, SignalStore, mangle/global/client_only helpers
- query.rs — Query trait, CacheKey, query_one!/query_all! macros
  (macro paths updated from $crate::framework::* to $crate::*)
- context.rs — RenderContext, ComponentTree, ComponentNode
- connection.rs — ConnectionManager, SubscriptionRegistry, ConnectionState
- sse.rs — format_patch_elements, format_patch_signals
- server.rs — AppState, SharedState, sse_handler (pure framework plumbing)

Todo example (examples/todo/):
- main.rs — SQLite setup, seeding, server bootstrap
- app.rs — router, document_shell, resolve_and_render, render_page,
  action_then_render, and all HTTP handlers
- queries.rs — Todo model, ListTodos/GetTodo queries, mutation helpers
- todo_list.rs — TodoList page component
- about.rs — About page component

Run the example independently with: cargo run --example todo

https://claude.ai/code/session_01JThiQbp3Bn9J1VhBpRuz4u

examples/todo/queries.rs

@@ -0,0 +1,75 @@
+use livevue_rs::CacheKey;
+use serde::{Deserialize, Serialize};
+
+// ---------------------------------------------------------------------------
+// Models
+// ---------------------------------------------------------------------------
+
+/// A single todo item. Maps to the `todos` SQLite table.
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct Todo {
+    pub id: i64,
+    pub title: String,
+    pub completed: bool,
+}
+
+// ---------------------------------------------------------------------------
+// Read queries (go through cx.run / Query trait)
+// ---------------------------------------------------------------------------
+
+/// Fetch all todos, ordered by id.
+pub struct ListTodos;
+
+livevue_rs::query_all!(ListTodos {
+    sql: "SELECT id, title, completed FROM todos ORDER BY id",
+    params: [],
+    output: Todo,
+    cache: |_s: &ListTodos| CacheKey::Table { table: "todos" },
+});
+
+/// Fetch a single todo by id.
+pub struct GetTodo {
+    pub id: i64,
+}
+
+livevue_rs::query_one!(GetTodo {
+    sql: "SELECT id, title, completed FROM todos WHERE id = ?",
+    params: [|s: &GetTodo| s.id],
+    output: Todo,
+    cache: |s: &GetTodo| CacheKey::PrimaryKey { table: "todos", id: s.id },
+});
+
+// ---------------------------------------------------------------------------
+// Write operations (plain sqlx, not through Query trait)
+// ---------------------------------------------------------------------------
+//
+// Mutations don't go through cx.run() because they're not reads and don't
+// produce subscription keys. They're called directly by action handlers,
+// which then trigger a full rerender.
+
+/// Insert a new todo. Returns the new row's id.
+pub async fn create_todo(db: &sqlx::SqlitePool, title: &str) -> anyhow::Result<i64> {
+    let result = sqlx::query("INSERT INTO todos (title, completed) VALUES (?, false)")
+        .bind(title)
+        .execute(db)
+        .await?;
+    Ok(result.last_insert_rowid())
+}
+
+/// Toggle a todo's completed status.
+pub async fn toggle_todo(db: &sqlx::SqlitePool, id: i64) -> anyhow::Result<()> {
+    sqlx::query("UPDATE todos SET completed = NOT completed WHERE id = ?")
+        .bind(id)
+        .execute(db)
+        .await?;
+    Ok(())
+}
+
+/// Delete a todo by id.
+pub async fn delete_todo(db: &sqlx::SqlitePool, id: i64) -> anyhow::Result<()> {
+    sqlx::query("DELETE FROM todos WHERE id = ?")
+        .bind(id)
+        .execute(db)
+        .await?;
+    Ok(())
+}