fix: body-local #run of an unbridged shape fails loudly instead of silent garbage (issue 0182)

The body-local #run fold in emitCall was effectively dead (gated on
args.len==0, but the __ct comptime wrapper always carries the implicit
*Context arg), so every body-local #run fell through to a RUNTIME call:
bridgeable shapes lucked into the right value; an unbridgeable shape
(e.g. [2][]i64) ran over --- storage -> garbage, exit 0, no diagnostic.

Fold any is_comptime callee (gated !enclosing.is_comptime so nested
metatype calls in a comptime wrapper's dead body aren't folded). On a
tryEval bail, distinguish a BRIDGE bail (result can't regToValue-
materialize -> error: comptime init of 'X' failed: <reason> +
comptime_failed, build fails, symmetric with the global #run path) from
an EXECUTION bail (VM can't run the body, e.g. NaN/extern -> runtime
fallthrough, preserving types/0150), via comptime_vm.last_bail_was_bridge
(reset at tryEval entry, set only at regToValue). The const name is
threaded onto the wrapper (comptime_display_name) so the diagnostic reads
the source name, not __ct_N.

Regressions: diagnostics/1204 (negative), comptime/0645 (positive).
Verified by 3 adversarial reviews, suite 801/0.

src/ir/lower.zig

@@ -222,6 +222,12 @@ pub const Lowering = struct {
     suppress_int_fit_check: bool = false, // inside an explicit `xx` cast operand: truncation is requested, skip the literal fits-check
     block_counter: u32 = 0,
     comptime_counter: u32 = 0,
+    /// Transient: the user-facing const name of the body-local `#run` currently
+    /// being lowered (`L :: #run f()`), so `lowerInlineComptime` can stamp the
+    /// `__ct` wrapper's `comptime_display_name` for a friendly comptime-init
+    /// failure diagnostic (issue 0182). Set/cleared around the const's value
+    /// lowering; null for a bare inline `#run`.
+    comptime_const_name: ?[]const u8 = null,
     main_file: ?[]const u8 = null, // path of the main file; imported functions are declared extern
     resolved_root: ?*const Node = null, // full AST root (for building comptime modules)
     comptime_param_nodes: ?std.StringHashMap(*const Node) = null, // active comptime substitutions