chore(lint): allowlist the guarded GcHeader probe in collection_proto_thunks (#6659) (#6722)

#6659 (fac2bbe) added a `(ptr as *const u8).sub(GC_HEADER_SIZE) as *const GcHeader`
obj_type probe in collection_proto_thunks.rs without an addr-class allowlist entry,
so the address-classification audit (the `lint` gate) went red on main and on every
open PR branched from it.

The probe is correctly magnitude-classified — it runs only inside
`if is_above_handle_band(ptr) && is_valid_obj_ptr(ptr as *const u8)`, so the pointer
is never a handle-band small integer at the deref. Add the standard allowlist entry
(same shape as the sibling object/* probes) with a follow-up note to migrate it to
`addr_class::try_read_gc_header`.

Restores lint to green; no functional change.

Co-authored-by: Ralph <ralph@skelpo.com>

Author: proggeramlug

scripts/addr_class_allowlist.txt

@@ -137,6 +137,7 @@ crates/perry-runtime/src/object/global_this/ | * | pre-existing GcHeader probe p
 crates/perry-runtime/src/object/class_registry/ | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of class_registry.rs)
 crates/perry-runtime/src/object/descriptor_state.rs | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of object/mod.rs)
 crates/perry-runtime/src/object/to_string_tag.rs | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of object/mod.rs)
+crates/perry-runtime/src/object/collection_proto_thunks.rs | * | GcHeader obj_type probe guarded by is_above_handle_band + is_valid_obj_ptr (magnitude-classified before the deref); migrate to addr_class::try_read_gc_header in a follow-up (added in #6659)
 crates/perry-runtime/src/symbol/ | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of symbol.rs)
 crates/perry-runtime/src/typedarray/ | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of typedarray/mod.rs)
 crates/perry-runtime/src/process/ | * | pre-existing GcHeader probe predating addr_class; address validated by call-site guards (magnitude/registry/is_valid_obj_ptr) -- migrate to addr_class::try_read_gc_header in a follow-up (split of process.rs)