Merge branch 'pratik/otel-phase2-rpc-tracing' into pratik/otel-phase3-tx-tracing

Signed-off-by: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>

include/xrpl/telemetry/Redaction.h

@@ -0,0 +1,56 @@
+#pragma once
+
+/** Account-address redaction for telemetry span attributes.
+
+    Path-finding RPC handlers would otherwise emit the caller's raw
+    account addresses as span attributes. To keep addresses out of the
+    telemetry backend, they are hashed at the point of emission. This
+    header exposes a single pure helper that turns an address into a
+    short, stable, non-reversible token.
+
+    Data flow:
+
+        handler -> redactAccount(addr) -> span attribute -> OTLP export
+
+    The returned token is the first 16 hex characters (lowercase) of the
+    SHA-512Half digest of the address. It is deterministic (same address
+    always maps to the same token) so operators can still correlate spans
+    for a given account, but the original address cannot be recovered.
+
+    A second, independent hashing layer runs in the OpenTelemetry
+    Collector (an `attributes/hash` processor) as defense-in-depth for
+    any node that emits a raw value.
+
+    @note This function is pure and reentrant: it holds no global state,
+    performs no I/O, and is safe to call concurrently from any thread.
+
+    Usage example:
+    @code
+        #include <xrpl/telemetry/Redaction.h>
+        using namespace xrpl::telemetry;
+
+        span.setAttribute(
+            pathfind_span::attr::sourceAccount, redactAccount(src.asString()));
+    @endcode
+
+    Edge case (empty input yields empty output):
+    @code
+        assert(redactAccount("") == "");
+    @endcode
+*/
+
+#include <string>
+#include <string_view>
+
+namespace xrpl::telemetry {
+
+/** Hash an account address into a short, stable, non-reversible token.
+
+    @param addr  The account address to redact (e.g. an r-address).
+    @return The first 16 lowercase hex characters of sha512Half(addr),
+            or an empty string when @p addr is empty.
+*/
+[[nodiscard]] std::string
+redactAccount(std::string_view addr);
+
+}  // namespace xrpl::telemetry