feat: expose internal debug API handler (#255)

## Why this should be merged

This allows exposing a number of APIs exposed by Geth's [`debug`
namespace](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug).
Specifically:
-
[debug_blockProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugblockprofile)
- [debug_cpuProfile
](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugcpuprofile)
- [debug_freeOSMemory
](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugfreeosmemory)
-
[debug_gcStats](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debuggcstats)
- [debug_goTrace
](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debuggotrace)
-
[debug_memStats](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugmemstats)
-
[debug_mutexProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugmutexprofile)
-
[debug_setBlockProfileRate](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugsetblockprofilerate)
-
[debug_setGCPercent](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugsetgcpercent)
-
[debug_setMutexProfileFraction](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugsetmutexprofilefraction)
-
[debug_stacks](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugstacks)
-
[debug_startCPUProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugstartcpuprofile)
-
[debug_startGoTrace](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugstartgotrace)
-
[debug_stopCPUProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugstopcpuprofile)
-
[debug_stopGoTrace](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugstopgotrace)
-
[debug_verbosity](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugverbosity)
-
[debug_vmodule](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugvmodule)
-
[debug_writeBlockProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugwriteblockprofile)
-
[debug_writeMemProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugwritememprofile)
-
[debug_writeMutexProfile](https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-debug#debugwritemutexprofile)

Note: This is _not_ the full debug namespace.

## How this works

Simply re-exports the API, similarly to how the `ethapi`s are
re-exported.

## How this was tested

N/A

libevm/debug/api.go

@@ -0,0 +1,23 @@
+// Copyright 2026 the libevm authors.
+//
+// The libevm additions to go-ethereum are free software: you can redistribute
+// them and/or modify them under the terms of the GNU Lesser General Public License
+// as published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The libevm additions are distributed in the hope that they will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+// Package debug exposes the internal debug package.
+package debug
+
+import "github.com/ava-labs/libevm/internal/debug"
+
+// Handler is the debug API handler for tracking process level statistics.
+var Handler = debug.Handler