refactor(compress): move CCtx construction policy to Rust

Move reset, parameter copy, and default policy resolution from
ZSTD_makeCCtxParamsFromCParams into Rust through a pointer-based ABI function.
Keep the private LDM adjustment and its invariants in C while Rust owns the
stable parameter-object policy and focused reset/resolution coverage.

Test Plan:
- worker git diff and capped format checks
- parent capped root clippy and native build
- parent capped upstream make -j1 -C tests test
- parent capped CLI clippy and tests

All parent verification is serial under a 40 GiB virtual-memory cap. Standalone
root Rust unit linking remains unavailable because the crate imports C-owned
bridge symbols.

lib/compress/zstd_compress.c

@@ -2015,6 +2015,9 @@ int ZSTD_rust_cctx_params_job_size_min(void);
 int ZSTD_rust_cctx_params_job_size_max(void);
 ZSTD_CCtx_params* ZSTD_rust_createCCtxParams(ZSTD_customMem customMem);
 size_t ZSTD_rust_freeCCtxParams(ZSTD_CCtx_params* params);
+void ZSTD_rust_makeCCtxParamsFromCParams(
+        ZSTD_CCtx_params* cctxParams,
+        const ZSTD_compressionParameters* cParams);
 void ZSTD_rust_CCtxParams_init_internal(
         ZSTD_CCtx_params* cctxParams, const ZSTD_parameters* params,
         int compressionLevel);
@@ -3615,23 +3618,14 @@ static ZSTD_CCtx_params ZSTD_makeCCtxParamsFromCParams(
         ZSTD_compressionParameters cParams)
 {
     ZSTD_CCtx_params cctxParams;
-    /* should not matter, as all cParams are presumed properly defined */
-    ZSTD_CCtxParams_init(&cctxParams, ZSTD_CLEVEL_DEFAULT);
-    cctxParams.cParams = cParams;
-
-    /* Adjust advanced params according to cParams */
-    cctxParams.ldmParams.enableLdm = ZSTD_resolveEnableLdm(cctxParams.ldmParams.enableLdm, &cParams);
+    /* Rust owns reset, copy, and default policy.  Keep the C LDM adapter and
+     * assertions here because they depend on the private C parameter type. */
+    ZSTD_rust_makeCCtxParamsFromCParams(&cctxParams, &cParams);
     if (cctxParams.ldmParams.enableLdm == ZSTD_ps_enable) {
         ZSTD_ldm_adjustParameters(&cctxParams.ldmParams, &cParams);
         assert(cctxParams.ldmParams.hashLog >= cctxParams.ldmParams.bucketSizeLog);
         assert(cctxParams.ldmParams.hashRateLog < 32);
     }
-    cctxParams.postBlockSplitter = ZSTD_resolveBlockSplitterMode(cctxParams.postBlockSplitter, &cParams);
-    cctxParams.useRowMatchFinder = ZSTD_resolveRowMatchFinderMode(cctxParams.useRowMatchFinder, &cParams);
-    cctxParams.validateSequences = ZSTD_resolveExternalSequenceValidation(cctxParams.validateSequences);
-    cctxParams.maxBlockSize = ZSTD_resolveMaxBlockSize(cctxParams.maxBlockSize);
-    cctxParams.searchForExternalRepcodes = ZSTD_resolveExternalRepcodeSearch(cctxParams.searchForExternalRepcodes,
-                                                                             cctxParams.compressionLevel);
     assert(!ZSTD_checkCParams(cParams));
     return cctxParams;
 }