Phase 13.22.ADF: enable recursive subframe loading in read_tree

One-line fix: read_tree line 5298 load_subframes=False → True.
export_tree already writes nested subframes recursively (Phase 13.20).
read_tree now loads them recursively too.

E2_2 (nested subframe roundtrip): was FAILING since Phase 13.20, now PASSES.
1523 passed (+2 vs 1521 baseline), 6F+1E pre-existing.

Metadata skip (A3) reverted — read_tree depends on subframe UserInfo
for column_dtypes. Deferred: needs write-minimal-UserInfo approach.
Removed test_M1_metadata_skip.py (tested the reverted feature).

Author: miranov25

UTILS/dfextensions/AliasDataFrame/AliasDataFrame.py

@@ -5275,12 +5275,13 @@ def read_branch(branch_name):
                     last_error = None
                     for sf_treename in tree_names_to_try:
                         try:
-                            # load_subframes=False prevents recursive subframe loading
+                            # Phase 13.22.ADF: recursive subframe loading enabled.
+                            # Subframes of subframes are now loaded automatically.
                             sf = AliasDataFrame.read_tree(
                                 filename,
                                 treename=sf_treename,
                                 num_workers=num_workers,
-                                load_subframes=False
+                                load_subframes=True
                             )
                             break  # Found it!
                         except (ValueError, KeyError) as e: