fix(parser): parse braced defer { … } body as a statement block (issue 0065)

A braced `defer` body routed through `parseExpr` + a mandatory trailing
`;`, so it parsed the `{ … }` as a block-EXPRESSION whose statement loop
doesn't handle a destructure decl or a `catch`-statement — `defer { v, e
:= f(); … }` and `defer { x() catch e … }` failed with "expected ';'",
and even `defer { stmt; }` needed a spurious trailing semicolon.

Now the `kw_defer` arm parses a braced body with `parseBlock` (the same
path `onfail` uses), so every statement form works; the bare-expression
form (`defer expr;`) is unchanged. `in_defer_body` is still set before
parsing, so the cleanup-body control-flow bans (return/break/continue/
try/raise) and the E1.7 failable-absorption check still fire.

Resolves the `defer` manifestation of issue 0065 (the general
value-block-in-binding-position destructure remains open). Regression:
examples/1050-errors-defer-block-body.sx.

Gates: zig build, zig build test, run_examples.sh -> 341 passed, 0 failed.

examples/1050-errors-defer-block-body.sx

@@ -0,0 +1,27 @@
+// A braced `defer { … }` body parses as a full statement block (like `onfail`),
+// so it supports every statement form — a destructure decl, a `catch`-statement,
+// nested var decls — not just a single bare expression. Previously `defer { … }`
+// routed through the expression parser and rejected those with "expected ';'".
+//
+// Regression (issue 0065).
+
+#import "modules/std.sx";
+
+E :: error { Bad }
+
+probe   :: () -> (s32, !E) { return 21; }
+failing :: () -> !E { raise error.Bad; }
+
+run :: () {
+    defer {
+        v, e := probe();                              // destructure decl
+        if !e { print("defer: v={}\n", v); }          // value live under the guard
+        failing() catch x print("defer: caught\n");   // catch-statement absorbs
+    }
+    print("body\n");
+}
+
+main :: () -> s32 {
+    run();
+    return 0;
+}

examples/expected/1050-errors-defer-block-body.exit

@@ -0,0 +1 @@
+0

examples/expected/1050-errors-defer-block-body.stderr

@@ -0,0 +1 @@
+

examples/expected/1050-errors-defer-block-body.stdout

@@ -0,0 +1,3 @@
+body
+defer: v=21
+defer: caught

issues/0065-block-expr-destructure-decl-parse.md

@@ -1,5 +1,15 @@
 # 0065 — block-expression body does not parse a destructure decl (`v, e := f();`)
 
+> **PARTIALLY RESOLVED (defer manifestation, this session).** A braced
+> `defer { … }` body now parses via `parseBlock` (src/parser.zig, the
+> `kw_defer` arm) instead of `parseExpr`, mirroring `onfail`. So
+> `defer { v, e := f(); … }`, `defer { x() catch e … }`, and plain
+> `defer { stmt; }` all parse and run. Regression:
+> `examples/1050-errors-defer-block-body.sx`. **Still open:** the
+> general *value-producing block in binding position*
+> (`y := { v, e := f(); v };`) — a distinct parser path — does not parse
+> a destructure decl; see the second reproduction below.
+
 ## Symptom
 
 A destructure declaration (`v, e := f();`) inside a **block used in

src/parser.zig

@@ -2019,15 +2019,23 @@ pub const Parser = struct {
             return try self.createNode(start, .{ .return_stmt = .{ .value = value } });
         }
 
-        // Defer statement: defer <expr>;
+        // Defer statement: defer { body } | defer <expr>;
+        // A braced body parses as a full statement block (like `onfail`), so it
+        // supports every statement form (destructure, `catch`-statement, …); the
+        // bare-expression form keeps its trailing `;`.
         if (self.current.tag == .kw_defer) {
             const start = self.current.loc.start;
             self.advance();
             const saved_defer = self.in_defer_body;
             self.in_defer_body = true;
             defer self.in_defer_body = saved_defer;
-            const deferred = try self.parseExpr();
-            try self.expect(.semicolon);
+            const deferred: *Node = if (self.current.tag == .l_brace)
+                try self.parseBlock()
+            else blk: {
+                const e = try self.parseExpr();
+                try self.expect(.semicolon);
+                break :blk e;
+            };
             return try self.createNode(start, .{ .defer_stmt = .{ .expr = deferred } });
         }