Fix: Sort the contract manifest in byte order, not the machine's

The manifest is written in byte order, but both the runner and the manifest
contract discovered contracts with a bare `sort` and compared them with bash's
`<` -- and both of those follow LC_COLLATE. Under en_US.UTF-8 the collation
folds punctuation away, so `calendar_agenda_bridge_test.py` sorts before
`calendar-agenda-helper-contract` instead of after it, and eight pairs that
differ only by `-` against `_` come back out of order.

The effect was that `tests/setup/contract-manifest-contract` failed on this
machine, and `panama test` refused to run at all, with eight identical "paths
are not lexicographically sorted" findings and nothing naming which paths. A
gate whose answer depends on the machine's LANG is not a gate, so the sort and
the comparison are both pinned to byte order. LC_ALL rather than LC_COLLATE,
because an exported LC_ALL outranks it and would have put the bug back.

Claude-Session: https://claude.ai/code/session_017zzbtfnMLoYrB8WesqANFY

tests/setup/contract-manifest-contract

@@ -11,16 +11,22 @@ manifest="$repo_dir/tests/contracts.manifest"
 
 discover_contracts() {
     discovered_contracts=()
+    # Byte order, exactly as the runner discovers them. A UTF-8 collation folds
+    # the punctuation away and reorders the pairs that differ only by `-` and
+    # `_`, so a manifest correct here would be wrong on a machine with a
+    # different LANG.
     while IFS= read -r path; do
         [[ -x "$path" || "$path" == *_test.py ]] || continue
         discovered_contracts+=("tests/${path#"$repo_dir/tests/"}")
     done < <(find "$repo_dir/tests" -type f \
-        -not -path '*/fixtures/*' -not -path '*__pycache__*' | sort)
+        -not -path '*/fixtures/*' -not -path '*__pycache__*' | LC_ALL=C sort)
 }
 
 validate_manifest() {
     local candidate="$1"
     local -n expected_contracts="$2"
+    # Byte order, for the same reason discover_contracts sorts in it.
+    local LC_ALL=C
     local line capabilities path extra previous_comment="" previous_was_comment=0
     local -a capability_list=()
     local -A manifest_paths=() capability_counts=()