fix(install): trailing-comma regex breaks on commas inside string values

[fdcp]

Problem

code_review_graph/skills.py:417 uses a regex to strip trailing commas before } or ] when reading existing config files for merge:

stripped = re.sub(r',(\s*[}\]])', r'\1', stripped)

This regex does not track JSON string boundaries. If a string value contains a comma followed by } or ] on the next line, the regex will incorrectly remove the comma inside the string, producing invalid JSON that the subsequent json.loads silently misparses (or rejects outright).

Concrete breakage

A user config like:

{
  "mcp": {
    "my-server": {
      "command": ["x"],
      "description": "foo, bar",
    }
  }
}

becomes (after the regex pass):

{
  "mcp": {
    "my-server": {
      "command": ["x"],
      "description": "foo bar",
    }
  }
}

The comma inside "foo, bar" is deleted, silently corrupting the user's string value. Worse: a real ] or } inside a string (e.g. "see [docs]") will also be touched.

Same bug class as the _strip_jsonc_comments issue fixed in #530 (commit 47a43dc) — that one was string-aware and resolved cleanly; this one is a leftover raw regex that needs the same treatment.

Reproduction

import re
raw = '{"a": "foo, bar", "b": 1}'
print(re.sub(r',(\s*[}\]])', r'\1', raw))
# -> {"a": "foo bar", "b": 1}   ← comma inside string deleted

Suggested fix

Fold the trailing-comma strip into the existing stateful _strip_jsonc_comments scanner (introduced in #530) so both passes happen in one string-aware walk. The scanner already tracks string boundaries; extending it to also drop a , when the next non-whitespace token is } or ] is a small change and removes the need for the post-pass regex entirely.

Sketch:

def _strip_jsonc_and_trailing_commas(text: str) -> str:
    # same state machine as _strip_jsonc_comments, plus:
    #   in_state == "code" and c == "," and the next non-ws
    #   char is "}" or "]" -> drop the comma

Rename _strip_jsonc_comments -> _strip_jsonc_and_trailing_commas and delete the re.sub line at 417.

Out of scope for #530

Owner (@tirth8205) confirmed in #530 (comment) that this is out of scope for the spec-compliance PR and asked for a separate follow-up issue. Filing per that request.

Acceptance

• Add a test case with commas inside strings followed by } / ] to confirm the strip is string-aware
• Remove the raw re.sub at line 417
• Full suite green (was 1282 at fix(install): write opencode MCP config in official schema #530 merge time)

[Huaian666]

same here but only on the latest version. previous release was fine fwiw. had to pin the old version