feat(rust): migrate high-level runtime paths

Move long-distance matching and high-level decompression from C shims into
Rust. The decoder now owns context, dictionary, parameter, one-shot, and
buffered streaming state while C retains allocation/configuration, legacy,
and trace leaves.

Move CLI parsing, safety policy, and dispatch into a separate Rust static
archive. Keeping it separate prevents library builds from retaining FIO
symbols, while C continues to own file opening, replacement, and I/O.
Program targets now select matching compression/decompression archives.

The remaining C boundary is intentional: high-level compression, optimal
parsing, dictionary building, legacy callbacks, and CLI file I/O still need
migration.

Test Plan:
- cargo test --all-targets (native and i686)
- cargo test --all-targets in rust/cli (native and i686)
- CLI crate compression-only and decompression-only feature tests
- native and i686 fuzzer/zstreamtest runs, plus legacy and dictionary tests
- ZSTD_C_PREDICT and ZSTD_HEAPMODE=0 fuzzer coverage
- library, dynamic-link, and program-target build/round-trip matrix

Refs: rust/README.md

programs/fileio.c

@@ -501,6 +501,11 @@ void FIO_setNbFilesTotal(FIO_ctx_t* const fCtx, int value)
     fCtx->nbFilesTotal = value;
 }
 
+void FIO_setHasStdinInput(FIO_ctx_t* const fCtx, int value)
+{
+    fCtx->hasStdinInput = value != 0;
+}
+
 void FIO_determineHasStdinInput(FIO_ctx_t* const fCtx, const FileNamesTable* const filenames) {
     size_t i = 0;
     for ( ; i < filenames->tableSize; ++i) {