tools/epro2/kicad: fix two --all crashes found running the other 4 Pro projects

Running the new --all on the remaining 4 Pro projects (X86 motherboard,
220V power supply, Taishan Pi, Liangshan Pi) surfaced two crash modes
not covered by ESP-VoCat:

1. Odd inner-layer count → KiCad rejects the file at load with
   "3 is not a valid layer count". The 220V power boards have one
   used inner SIGNAL layer (3 copper total: F.Cu / In1.Cu / B.Cu),
   but KiCad requires an even copper count. Fixed pcb_writer to pad
   with one empty inner layer when the inner count is odd, so the
   total stays even (2, 4, 6, ...).

2. Two BOARDs sharing the same META.title — twin "显示板" boards in
   the 220V power project — landed in the same project directory
   and the second silently overwrote the first's .kicad_sch /
   .kicad_pcb / .kicad_pro. Fixed --all to detect title collisions
   and suffix every colliding basename with the BOARD uuid prefix
   (so both '显示板' boards become '显示板_52e8cc76' and
   '显示板_55d32906' rather than one quietly winning).

71 → 73 unit tests pass (test_odd_inner_signal_count_padded_to_even_total
+ test_duplicate_board_titles_get_distinct_basenames).

Tangentially noted while running this: Taishan Pi and Liangshan Pi are
Pro 2.x JSON, not EPRO2 streams — our replay layer reads the files but
doesn't decode docType, so SCH/PCB grouping returns nothing. Pro 2.x
needs a separate writer; out of scope for this commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/epro2/kicad/__main__.py

@@ -221,10 +221,26 @@ def _convert_all_projects(
 
     page_groups = _group_pages_by_sch(proj)  # SCH-uuid → [page-uuid, ...]
 
+    # Resolve basename collisions: two distinct BOARDs with the same title
+    # (seen on the 220V power project — twin "显示板" boards) would otherwise
+    # share a directory and overwrite each other's files. When the same
+    # basename appears multiple times, suffix EVERY occurrence with the
+    # board uuid prefix so each project dir stays unambiguous (instead of
+    # quietly handing one of them the unsuffixed name).
+    base_counts: dict[str, int] = {}
+    for board_id, slot in boards.items():
+        title = slot["title"] or board_id[:12]
+        base_counts[_project_basename(title)] = base_counts.get(_project_basename(title), 0) + 1
+    basenames: dict[str, str] = {}
+    for board_id, slot in boards.items():
+        title = slot["title"] or board_id[:12]
+        base = _project_basename(title)
+        basenames[board_id] = base if base_counts[base] == 1 else f"{base}_{board_id[:8]}"
+
     n = 0
     for board_id, slot in boards.items():
         title = slot["title"] or board_id[:12]
-        basename = _project_basename(title)
+        basename = basenames[board_id]
         proj_dir = out_dir / basename
         proj_dir.mkdir(parents=True, exist_ok=True)
         sch_doc = slot["sch"]