refactor(compress): expose stream size and level leaves from Rust

Move the public stream-size and predefined compression-level leaves to their
caller-facing Rust symbols, removing the remaining C-only forwarding bodies.
Keep crate-local aliases where Rust implementation modules still use the old
internal names, while the public C ABI now lands directly in Rust.

Test Plan: Nightly Rust formatting and staged diff checks passed; capped native and upstream gates pending.

lib/compress/zstd_compress.c

@@ -1554,8 +1554,6 @@ typedef char ZSTD_rust_next_input_size_hint_mt_or_st_state_layout[
         ? 1 : -1];
 size_t ZSTD_rust_nextInputSizeHintMTorST(
         const ZSTD_rust_nextInputSizeHintMTorSTState* state);
-size_t ZSTD_rust_CStreamInSize(void);
-size_t ZSTD_rust_CStreamOutSize(void);
 size_t ZSTD_rust_sizeofCDict(size_t objectSize, size_t workspaceSize);
 size_t ZSTD_rust_sizeofLocalDict(int dictBufferPresent, size_t dictSize,
                                  size_t cdictSize);
@@ -1925,9 +1923,6 @@ void ZSTD_rust_setBufferExpectations(
  * sanitizer workspace policy, which it feeds to the leaves as explicit
  * scalar inputs.  The ZSTD_CParamMode_e and ZSTD_ParamSwitch_e enums are
  * passed as int; the Rust side mirrors their values. */
-int ZSTD_rust_params_maxCLevel(void);
-int ZSTD_rust_params_minCLevel(void);
-int ZSTD_rust_params_defaultCLevel(void);
 ZSTD_bounds ZSTD_rust_params_getBounds(int param);
 size_t ZSTD_rust_params_checkCParams(ZSTD_compressionParameters cParams);
 void ZSTD_rust_params_assertEqualCParams(ZSTD_compressionParameters cParams1,
@@ -7547,13 +7542,6 @@ size_t ZSTD_freeCStream(ZSTD_CStream* zcs)
 
 /*======   Initialization   ======*/
 
-size_t ZSTD_CStreamInSize(void)  { return ZSTD_rust_CStreamInSize(); }
-
-size_t ZSTD_CStreamOutSize(void)
-{
-    return ZSTD_rust_CStreamOutSize();
-}
-
 static ZSTD_CParamMode_e ZSTD_getCParamMode(ZSTD_CDict const* cdict, ZSTD_CCtx_params const* params, U64 pledgedSrcSize)
 {
     int const cdict_present = cdict != NULL;
@@ -8653,10 +8641,6 @@ size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output)
 /* The compression-level tables (formerly included from clevels.h) live in
  * rust/src/zstd_compress_params.rs. */
 
-int ZSTD_maxCLevel(void) { return ZSTD_rust_params_maxCLevel(); }
-int ZSTD_minCLevel(void) { return ZSTD_rust_params_minCLevel(); }
-int ZSTD_defaultCLevel(void) { return ZSTD_rust_params_defaultCLevel(); }
-
 /**
  * Reverses the adjustment applied to cparams when enabling dedicated dict
  * search. This is used to recover the params set to be used in the working