fix: revert all unrelated upstream develop changes from phase-7 PR

Reverts 259 files that carried unrelated upstream changes through the
phase-6 merge: enum class removals (cppcoreguidelines-use-enum-class),
scoped_lock→lock_guard conversions (modernize-use-scoped-lock),
nodestore Backend API changes (void const* key), .clang-tidy config,
test infrastructure deletions, and miscellaneous develop changes.

These changes belong on develop, not in the telemetry PR chain.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

include/xrpl/protocol/STBase.h

@@ -18,6 +18,8 @@ struct JsonOptions
     using underlying_t = unsigned int;
     underlying_t value;
 
+    // Bitwise flags with operator~
+    // NOLINTNEXTLINE(cppcoreguidelines-use-enum-class)
     enum values : underlying_t {
         // clang-format off
         none                        = 0b0000'0000,