Fix DSN tokenizer to accept KiCad net names like /*52

Specctra's SpecCharASCII includes / and *, and an Identifier may start with /,
so KiCad emits hierarchical net names such as /*52 and /53. The tokenizer
treated any /* as a block-comment start and raised 'unterminated comment' when
no */ followed — rejecting real KiCad DSN. Match FreeRouting's JFlex rule-order
resolution: /* is a comment only when a closing */ exists; otherwise it is an
ordinary name run. Validated against a KiCad 10.0.4 pcbnew-exported DSN (78 nets
incl. /*52, /53).

src/freeroute/dsn/tokenizer.py

@@ -126,13 +126,19 @@ def tokenize(text: str, quote_chars: str = _QUOTES) -> list[Token]:
             eol = text.find("\n", i)
             i = n if eol == -1 else eol
             continue
-        if ch == "/" and i + 1 < n and text[i + 1] == "*":  # block comment
+        # `/* ... */` is a block comment ONLY when a closing `*/` exists.
+        # SpecCharASCII includes `/` and `*`, and an Identifier may start with
+        # `/`, so KiCad emits net names like `/*52`. FreeRouting's JFlex scanner
+        # resolves the ambiguity by longest-match / rule-order: with no closing
+        # `*/`, the comment rule fails and the run is read as a name. Mirror
+        # that — an unclosed `/*` is an ordinary token, not an error.
+        if ch == "/" and i + 1 < n and text[i + 1] == "*":
             end = text.find("*/", i + 2)
-            if end == -1:
-                raise DsnSyntaxError(f"unterminated /* */ comment at line {line}")
-            line += text.count("\n", i, end)
-            i = end + 2
-            continue
+            if end != -1:
+                line += text.count("\n", i, end)
+                i = end + 2
+                continue
+            # no closing `*/` — fall through and read `/*...` as a normal token
 
         # Brackets -----------------------------------------------------------
         if ch == "(":