Initial dstalk project: core DLL + CLI + BearSSL TLS

- Core DLL: AI API client (DeepSeek/OpenAI compatible), HTTP(S) via Boost.Beast
- BearSSL vendored as TLS backend (MIT license, replacing OpenSSL)
- CLI frontend with ANSI colors, /help /model /file /save /load commands
- WinHTTP alternative HTTP client for Windows
- GPLv3 license with linking exception
- Build: CMake + Ninja + Clang, dependencies via Conan2

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

dstalk-core/thirdparty/bearssl/src/hash/md5sha1.c

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see bearssl.h */
+void
+br_md5sha1_init(br_md5sha1_context *cc)
+{
+	cc->vtable = &br_md5sha1_vtable;
+	memcpy(cc->val_md5, br_md5_IV, sizeof cc->val_md5);
+	memcpy(cc->val_sha1, br_sha1_IV, sizeof cc->val_sha1);
+	cc->count = 0;
+}
+
+/* see bearssl.h */
+void
+br_md5sha1_update(br_md5sha1_context *cc, const void *data, size_t len)
+{
+	const unsigned char *buf;
+	size_t ptr;
+
+	buf = data;
+	ptr = (size_t)cc->count & 63;
+	while (len > 0) {
+		size_t clen;
+
+		clen = 64 - ptr;
+		if (clen > len) {
+			clen = len;
+		}
+		memcpy(cc->buf + ptr, buf, clen);
+		ptr += clen;
+		buf += clen;
+		len -= clen;
+		cc->count += (uint64_t)clen;
+		if (ptr == 64) {
+			br_md5_round(cc->buf, cc->val_md5);
+			br_sha1_round(cc->buf, cc->val_sha1);
+			ptr = 0;
+		}
+	}
+}
+
+/* see bearssl.h */
+void
+br_md5sha1_out(const br_md5sha1_context *cc, void *dst)
+{
+	unsigned char buf[64];
+	uint32_t val_md5[4];
+	uint32_t val_sha1[5];
+	size_t ptr;
+	unsigned char *out;
+	uint64_t count;
+
+	count = cc->count;
+	ptr = (size_t)count & 63;
+	memcpy(buf, cc->buf, ptr);
+	memcpy(val_md5, cc->val_md5, sizeof val_md5);
+	memcpy(val_sha1, cc->val_sha1, sizeof val_sha1);
+	buf[ptr ++] = 0x80;
+	if (ptr > 56) {
+		memset(buf + ptr, 0, 64 - ptr);
+		br_md5_round(buf, val_md5);
+		br_sha1_round(buf, val_sha1);
+		memset(buf, 0, 56);
+	} else {
+		memset(buf + ptr, 0, 56 - ptr);
+	}
+	count <<= 3;
+	br_enc64le(buf + 56, count);
+	br_md5_round(buf, val_md5);
+	br_enc64be(buf + 56, count);
+	br_sha1_round(buf, val_sha1);
+	out = dst;
+	br_range_enc32le(out, val_md5, 4);
+	br_range_enc32be(out + 16, val_sha1, 5);
+}
+
+/* see bearssl.h */
+uint64_t
+br_md5sha1_state(const br_md5sha1_context *cc, void *dst)
+{
+	unsigned char *out;
+
+	out = dst;
+	br_range_enc32le(out, cc->val_md5, 4);
+	br_range_enc32be(out + 16, cc->val_sha1, 5);
+	return cc->count;
+}
+
+/* see bearssl.h */
+void
+br_md5sha1_set_state(br_md5sha1_context *cc, const void *stb, uint64_t count)
+{
+	const unsigned char *buf;
+
+	buf = stb;
+	br_range_dec32le(cc->val_md5, 4, buf);
+	br_range_dec32be(cc->val_sha1, 5, buf + 16);
+	cc->count = count;
+}
+
+/* see bearssl.h */
+const br_hash_class br_md5sha1_vtable = {
+	sizeof(br_md5sha1_context),
+	BR_HASHDESC_ID(br_md5sha1_ID)
+		| BR_HASHDESC_OUT(36)
+		| BR_HASHDESC_STATE(36)
+		| BR_HASHDESC_LBLEN(6),
+	(void (*)(const br_hash_class **))&br_md5sha1_init,
+	(void (*)(const br_hash_class **, const void *, size_t))
+		&br_md5sha1_update,
+	(void (*)(const br_hash_class *const *, void *))
+		&br_md5sha1_out,
+	(uint64_t (*)(const br_hash_class *const *, void *))
+		&br_md5sha1_state,
+	(void (*)(const br_hash_class **, const void *, uint64_t))
+		&br_md5sha1_set_state
+};