tools/epro2/kicad: fix two KiCad 8 parse blockers (newline + pin_numbers)

装 kicad 8.0.9 (apt PPA) 后跑 kicad-cli sch erc 校验我们 emit 的
.kicad_sch 文件，发现 9/9 sheets 一开始全部报 "Failed to load schematic
file" — 父节点解析就挂掉。Bisect 找到两个语法 bug：

1. **(pin_numbers (hide no)) 不被 KiCad 8 接受**
   KiCad 8 lib_symbols 里 `pin_numbers` 是 token-form，不接受 (hide
   yes/no) 子块。要么省略整个 block 默认 visible，要么 `(pin_numbers
   hide)` 表示隐藏。原来的 `(hide no)` 风格是 KiCad 7 旧语法。

   Fix: tools/epro2/kicad/sym_writer.py 删掉 (pin_numbers (hide no))
        行；KiCad 默认 visible 行为正是我们想要的。

2. **String 里的字面 \n / \r / \t 让 KiCad 解析器中止**
   ESP-VoCat 的 Overview sheet 有 TEXT "Battary\n3.7V 700mAH"（多行
   电池标签），EPRO2 里以**字面 0x0a 字符**存储。我们把它原样 emit
   成 "..." 包住的字符串 → KiCad reader 在 quoted string 内遇到 \n
   就报 parse error 不给 message。

   Fix: tools/epro2/kicad/sexpr.py 在 str escape 路径加 \n / \r / \t
        转义；reader 加 \r 解码（roundtrip 用）。

修完后：

  9/9 sheets parse OK in KiCad 8.0.9
  ERC 跑通，9 个 sheet 共 2793 violations，分布：
     1372 endpoint_off_grid        (49%, cosmetic — 30-mil EPRO2 grid 不
                                    snap KiCad 默认 50-mil grid)
      571 lib_symbol_issues        (20%, cosmetic — facere 库未注册到
                                    user library table；库已 embed 在
                                    .kicad_sch 内联可用)
      444 wire_dangling            (16%, real — wire 端点没精确对齐 pin)
      406 pin_not_connected        (15%, 同上的另一面)

  Cosmetic 占 70%，real connectivity 30%，下个 phase 处理：
    - grid 校准（把 coord 精确 round 到统一 grid 上）
    - pin tip 端点匹配（KiCad 需要 wire 端点 == pin (at) 字段对应的
      绝对坐标，浮点必须精确相等）
    - 生成 sym-lib-table 注册 facere 库（消 lib_symbol_issues）

测试：
  + test_string_escapes_newlines_and_tabs
  + test_lib_symbol_omits_pin_numbers_block
  reader 加 \r 解码

41/41 通过（39 旧 + 2 新）。

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

tools/epro2/kicad/_sexpr_reader.py

@@ -32,7 +32,7 @@ def tokens(src: str) -> Iterator[str]:
                 ch = src[j]
                 if ch == "\\" and j + 1 < n:
                     nxt = src[j + 1]
-                    buf.append({"\\": "\\", '"': '"', "n": "\n", "t": "\t"}.get(nxt, nxt))
+                    buf.append({"\\": "\\", '"': '"', "n": "\n", "t": "\t", "r": "\r"}.get(nxt, nxt))
                     j += 2
                     continue
                 if ch == '"':

tools/epro2/kicad/sexpr.py

@@ -52,7 +52,15 @@ def _emit(value: Any, out: io.StringIO, indent: int, *, pretty: bool) -> None:
     elif isinstance(value, (int, float)):
         out.write(_fmt_number(value))
     elif isinstance(value, str):
-        escaped = value.replace("\\", "\\\\").replace('"', '\\"')
+        # KiCad's S-expr reader rejects literal newlines/CR/tabs inside
+        # quoted strings; we MUST escape them. Order matters: backslash first.
+        escaped = (
+            value.replace("\\", "\\\\")
+            .replace('"', '\\"')
+            .replace("\n", "\\n")
+            .replace("\r", "\\r")
+            .replace("\t", "\\t")
+        )
         out.write(f'"{escaped}"')
     elif value is None:
         # rare but sometimes a slot is intentionally empty

tools/epro2/kicad/sym_writer.py

@@ -165,9 +165,11 @@ def write_lib_symbol(doc: Document, *, lib_prefix: str = "facere") -> list | Non
                 [Sym("number"), pin_number or "~", _font()],
             ])
 
+    # KiCad 8 syntax: omit `(pin_numbers ...)` block entirely to mean "visible"
+    # (using `(pin_numbers (hide no))` is rejected as a parse error). To hide
+    # we'd emit the bare token `(pin_numbers hide)`.
     return [
         Sym("symbol"), f"{lib_prefix}:{part_id}",
-        [Sym("pin_numbers"), [Sym("hide"), Sym("no")]],
         [Sym("pin_names"), [Sym("offset"), 1.016]],
         [Sym("in_bom"), Sym("yes")],
         [Sym("on_board"), Sym("yes")],

tools/epro2/tests/test_sexpr.py

@@ -19,6 +19,24 @@ def test_string_escaping():
     assert parsed[1] == 'a "quote" + \\backslash'
 
 
+def test_string_escapes_newlines_and_tabs():
+    """KiCad 8 rejects literal newlines/CR/tabs inside quoted strings, so the
+    emitter must escape them. Round-trip restores the original characters."""
+    src = "Battary\n3.7V 700mAH\twith\rtab"
+    text = to_sexpr([Sym("text"), src], pretty=False)
+    # Raw text must NOT contain literal newline / CR / tab inside quotes
+    assert "\\n" in text
+    assert "\\r" in text
+    assert "\\t" in text
+    quoted = text[text.index('"'):text.rindex('"') + 1]
+    assert "\n" not in quoted
+    assert "\r" not in quoted
+    assert "\t" not in quoted
+    # Round-trip restores the original (our reader handles these escapes)
+    parsed = parse(text)
+    assert parsed[1] == src
+
+
 def test_float_formatting_strips_trailing_zeros():
     text = to_sexpr([Sym("x"), 1.500000], pretty=False)
     assert "1.5" in text

tools/epro2/tests/test_sym_writer.py

@@ -40,6 +40,17 @@ def test_write_lib_symbol_emits_outer_wrapper_and_body():
     assert inner[0][1] == "MyPart.1_1_1"
 
 
+def test_lib_symbol_omits_pin_numbers_block():
+    """KiCad 8 rejects (pin_numbers (hide no)). When pins should be visible
+    we must omit the pin_numbers block entirely (default = visible)."""
+    d = _sym_doc("sym1", "MyPart.1", [])
+    entry = write_lib_symbol(d)
+    text = to_sexpr(entry)
+    parsed = parse(text)
+    assert not _block(parsed, "pin_numbers"), \
+        "pin_numbers block should be omitted (KiCad 8 syntax)"
+
+
 def test_pin_renders_with_attr_pulled_metadata():
     d = _sym_doc("sym1", "MyPart.1", [
         ("e5", {"_type": "PIN", "partId": "MyPart.1",