Align ION_SPEC with the compiler and fix Ion snippets in the spec and writing-ion-code skills.

Author: Cod-e-Codes

.cursor/skills/writing-ion-code/SKILL.md

@@ -71,7 +71,9 @@ let items: Vec<MyStruct> = Vec::new(); // element type from annotation
 **Integer limits**
 
 ```ion
-if n == int::MIN { ... }
+if n == int::MIN {
+    return 0;
+}
 let cap: int = int::MAX;
 ```
 
@@ -91,7 +93,7 @@ Tuple values (flat only, no nesting): `let t: (int, int) = (1, 2);` then `t.0`,
 **Control flow**
 
 - `if` / `else if` / `else` conditions must be `bool`.
-- `while`, `loop`, `break`, `continue`, `for x in expr;` (`for` ends with `;` per grammar).
+- `while`, `loop`, `break`, `continue`, `for x in expr` over `Vec<T>`, `[T; N]`, or `String` (bytes as `u8`)
 - `match expr { Pattern => { ... } }` with guards `pattern if cond =>`.
 
 **Methods**

.cursor/skills/writing-ion-code/references/verified-patterns.md

@@ -78,7 +78,7 @@ let x: int = Box::unwrap(b);
 ```ion
 let arr: [int; 3] = [1, 2, 3];
 let fill: [u8; 4] = [0; 4];
-let slice: []int = arr;  // array to slice coercion
+let s: &[]int = &arr;  // array-to-slice coercion via borrow
 let elem: int = arr[0];  // bounds checked unless unsafe
 ```
 
@@ -147,9 +147,7 @@ Multi-file mode prefixes each module's C symbols (`io_print_int`, `fmt_print_int
 
 ## Channel send expressions
 
-`send(&tx, make())` is valid ([tests/test_channel_send_call_expr.ion](../../../../tests/test_channel_send_call_expr.ion)).
-
-Expression form `tx<-value` exists in grammar; prefer `send(&tx, value)` to match tests and examples.
+`send(&tx, make())` is valid ([tests/test_channel_send_call_expr.ion](../../../../tests/test_channel_send_call_expr.ion)). Use `send(&tx, value)` and `recv(&mut rx)` (see [examples/spawn_channel/spawn_channel.ion](../../../../examples/spawn_channel/spawn_channel.ion)).
 
 ## if / ownership merge
 
@@ -190,7 +188,7 @@ channel<&int>()
 spawn { use_ref(&x); };
 
 // use after move
-let v = Vec::new();
+let v: Vec<int> = Vec::new();
 let w = v;
 let _ = v.len();
 ```