feat: sparse checkout + shallow fetch для минимального трафика

- git_pull() использует fetch --depth 1 + reset (не качает историю)
- sparse checkout: скачивается только latest версия cli.js, не все
- Все старые версии остаются в репо, но клиент их не скачивает
- README обновлён с git clone --depth 1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

uclaude_updater.py

@@ -150,7 +150,7 @@ def ver_tuple(v):
 def git_pull():
     """Pull latest changes from remote (shallow fetch for minimal download)."""
     try:
-        # Shallow fetch + reset — downloads only latest snapshot, not full history
+        # Shallow fetch + reset — downloads only latest commit, not full history
         result = subprocess.run(
             ["git", "fetch", "--depth", "1", "origin", "master"],
             cwd=SCRIPT_DIR, capture_output=True, text=True, timeout=60,
@@ -170,6 +170,10 @@ def git_pull():
             ["git", "reset", "--hard", "origin/master"],
             cwd=SCRIPT_DIR, capture_output=True, text=True, timeout=10,
         )
+
+        # Setup sparse checkout to download only latest version's cli.js
+        _setup_sparse_checkout()
+
         return True
     except subprocess.TimeoutExpired:
         eprint(f"  {Y}git fetch timed out{D}")
@@ -179,6 +183,50 @@ def git_pull():
         return True
 
 
+def _setup_sparse_checkout():
+    """Configure sparse checkout to only include root files + latest release.
+
+    This avoids downloading cli.js for ALL versions (each ~12MB).
+    Only the latest version's cli.js is checked out.
+    """
+    index_path = os.path.join(SCRIPT_DIR, "claude", "releases", "index.json")
+    if not os.path.isfile(index_path):
+        return
+
+    try:
+        with open(index_path, "r") as f:
+            latest = json.load(f).get("latest")
+    except Exception:
+        return
+
+    if not latest:
+        return
+
+    # Enable sparse checkout
+    subprocess.run(
+        ["git", "config", "core.sparseCheckout", "true"],
+        cwd=SCRIPT_DIR, capture_output=True,
+    )
+
+    sparse_file = os.path.join(SCRIPT_DIR, ".git", "info", "sparse-checkout")
+    os.makedirs(os.path.dirname(sparse_file), exist_ok=True)
+
+    patterns = [
+        "/*",                                          # root files (updater, config, README)
+        "/claude/releases/index.json",                 # version index
+        f"/claude/releases/v{latest}/",                # latest release (cli.js + changelog + install)
+    ]
+
+    with open(sparse_file, "w") as f:
+        f.write("\n".join(patterns) + "\n")
+
+    # Apply sparse checkout
+    subprocess.run(
+        ["git", "checkout", "HEAD", "--", "."],
+        cwd=SCRIPT_DIR, capture_output=True, timeout=30,
+    )
+
+
 # ============================================================
 #  CLI.js installation
 # ============================================================