refactor(telemetry): remove unused SpanGuard::span(name) overload

Remove the single-arg span(name) factory that creates unconditional
spans without category gating. All call sites use the 3-arg
span(TraceCategory, prefix, name) variant which checks whether the
category is enabled in config before creating a span. The 1-arg form
was dead code with no callers.

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

include/xrpl/telemetry/SpanGuard.h

@@ -14,7 +14,6 @@
         +-------------------------------------------+
         | - impl_ : unique_ptr<Impl>  (pimpl)       |
         +-------------------------------------------+
-        | + span(name) : SpanGuard          [static] |
         | + span(cat, prefix, name)         [static] |
         | + childSpan(name) : SpanGuard              |
         | + linkedSpan(name) : SpanGuard             |
@@ -194,12 +193,6 @@ public:
 
     // --- Static factory methods ----------------------------------------
 
-    /** Create an unconditional span (always created if telemetry is on).
-        @param name  Full span name (e.g. "app.startup").
-    */
-    static SpanGuard
-    span(std::string_view name);
-
     /** Create a span guarded by a TraceCategory flag.
         The span name is built as "prefix.name". Returns a null guard
         if the category is disabled in config.
@@ -329,11 +322,6 @@ public:
     SpanGuard&
     operator=(SpanGuard const&) = delete;
 
-    static SpanGuard
-    span(std::string_view)
-    {
-        return {};
-    }
     static SpanGuard
     span(TraceCategory, std::string_view, std::string_view)
     {

src/libxrpl/telemetry/SpanGuard.cpp

@@ -20,8 +20,9 @@
 
 #ifdef XRPL_ENABLE_TELEMETRY
 
-#include <xrpl/telemetry/DiscardFlag.h>
 #include <xrpl/telemetry/SpanGuard.h>
+
+#include <xrpl/telemetry/DiscardFlag.h>
 #include <xrpl/telemetry/Telemetry.h>
 
 #include <opentelemetry/context/runtime_context.h>
@@ -131,15 +132,6 @@ isCategoryEnabled(Telemetry const& tel, TraceCategory cat)
     return false;  // unreachable, silences compiler warning
 }
 
-SpanGuard
-SpanGuard::span(std::string_view name)
-{
-    auto* tel = Telemetry::getInstance();
-    if (!tel || !tel->isEnabled())
-        return {};
-    return SpanGuard(std::make_unique<Impl>(tel->startSpan(name)));
-}
-
 SpanGuard
 SpanGuard::span(TraceCategory cat, std::string_view prefix, std::string_view name)
 {