feat(docs): add Chinese and English documentation for Mingling tutorials

Add comprehensive documentation covering Declare a Dispatcher, Declare a
Chain, Rendering Results, Multi-Command Program, Argument Parsing with
Picker and Clap, Program Setup, Error Handling, Help Info, Resource
System, Exit Code Control, Hook System, Testing, Completion, Structural
Rendering, and Core Concepts

1 files changed, 120 insertions, 0 deletions

diff --git a/docs/pages/9-error-handling.md b/docs/pages/9-error-handling.md
new file mode 100644
index 0000000..ec1f422
--- /dev/null
+++ b/docs/pages/9-error-handling.md
@@ -0,0 +1,120 @@
+<h1 align="center">Error Handling</h1>
+<p align="center">
+    Gracefully present errors to the user
+</p>
+
+A pipeline isn't just the happy path. When input is invalid, a resource isn't found, or an operation fails, you need a place to handle these "surprises" instead of letting the program panic.
+
+## Two Paths: Success vs. Error
+
+Recall the pipeline model: Chain's return value is `Next`, which has two destinations:
+
+| Route          | Meaning                                     |
+| -------------- | ------------------------------------------- |
+| `.to_render()` | Got a result, hand it to a Renderer to show |
+| `.to_chain()`  | Not done yet, hand it to the next Chain     |
+
+Error values can also take either path—you can render the error msg directly, or pass it to the next Chain for potential recovery.
+
+## Distinguish Errors with Dedicated Types
+
+```rust
+@@@dispatcher!("greet", CMDGreet => EntryGreet);
+pack!(ResultGreeting = String);
+pack!(ErrorNameEmpty = String);
+ 
+#[chain]
+fn handle_greet(args: EntryGreet) -> Next {
+    let name = args.inner.first().cloned().unwrap_or_default();
+ 
+    if name.is_empty() {
+        ErrorNameEmpty::new("name is required".to_string()).to_render()
+    } else {
+        ResultGreeting::new(name).to_render()
+    }
+}
+```
+ 
+Then write separate Renderers:
+
+```rust
+@@@dispatcher!("greet", CMDGreet => EntryGreet);
+@@@pack!(ResultGreeting = String);
+@@@pack!(ErrorNameEmpty = String);
+@@@#[chain] fn handle_greet(args: EntryGreet) -> Next { ResultGreeting::new(args.inner.first().cloned().unwrap_or_default()).to_render() }
+ 
+#[renderer]
+fn render_greeting(result: ResultGreeting) {
+    r_println!("Hello, {}!", *result);
+}
+ 
+#[renderer]
+fn render_error_name_empty(err: ErrorNameEmpty) {
+    r_println!("Error: {}", *err);
+}
+```
+ 
+Each Renderer does its own job; what the user sees depends on what the Chain returned.
+
+## Complete Example
+
+```rust
+dispatcher!("greet", CMDGreet => EntryGreet);
+ 
+pack!(ResultGreeting = String);
+pack!(ErrorNameEmpty = String);
+ 
+#[chain]
+fn handle_greet(args: EntryGreet) -> Next {
+    let name = args.inner.first().cloned().unwrap_or_default();
+    if name.is_empty() {
+        ErrorNameEmpty::new("name is required".to_string()).to_render()
+    } else {
+        ResultGreeting::new(name).to_render()
+    }
+}
+ 
+#[renderer]
+fn render_greeting(result: ResultGreeting) {
+    r_println!("Hello, {}!", *result);
+}
+ 
+#[renderer]
+fn render_error_name_empty(err: ErrorNameEmpty) {
+    r_println!("Error: {}", *err);
+}
+ 
+fn main() {
+    let mut program = ThisProgram::new();
+    program.with_dispatcher(CMDGreet);
+    program.exec_and_exit();
+}
+ 
+gen_program!();
+```
+ 
+Output:
+
+```text
+~# my-cli greet Alice
+Hello, Alice!
+ 
+~# my-cli greet
+Error: name is required
+```
+ 
+## About `pack_err!`
+
+If you've enabled `extra_macros`, you can use `pack_err!` to quickly declare an error type with an auto-generated `name` field:
+
+```rust
+// Features: ["extra_macros"]
+pack_err!(ErrorNotFound);
+// Generates: struct ErrorNotFound { pub name: String }
+```
+ 
+See [Feature List](pages/other/features) for details.
+
+<p align="center" style="font-size: 0.85em; color: gray;">
+    Written by @Weicao-CatilGrass
+</p>