docs: correct mermaid-py behavior in comments (remote API, not local Node.js)

mermaid-py (>=0.8.0, the version this project pins) validates diagrams by
sending them to a remote rendering service (https://mermaid.ink by default,
overridable via mermaid-py's own MERMAID_INK_SERVER env var), not by
spawning a local Node.js subprocess. Verified by inspecting the mermaid-py
0.8.0 and 0.8.4 source directly (mermaid/__main__.py uses requests.get()
against MERMAID_INK_SERVER, no subprocess/child_process anywhere).

This corrects two comments that describe the old (inaccurate, or possibly
just always-wrong) assumption:
- codewiki/src/be/utils.py: the _MERMAID_PY_BROKEN comment
- pyproject.toml: the nodejs build-requires comment

No functional change. The nodejs build-requires entry itself is left as-is
since I couldn't confirm whether it's needed for something else in the
project; flagging it for maintainers to reconsider.

Author: kiboook

codewiki/src/be/utils.py

@@ -151,8 +151,11 @@ def extract_mermaid_blocks(content: str) -> List[Tuple[int, str]]:
 # Skip it proactively so SpiderMonkey is never loaded into the process.
 _PYTHONMONKEY_BROKEN = sys.version_info >= (3, 12)
 
-# mermaid-py spawns a Node.js subprocess that can hang indefinitely (e.g. when
-# Node.js is missing or the mermaid CLI is misconfigured).  Enabled by default;
+# mermaid-py validates diagrams by sending them to a remote rendering service
+# (https://mermaid.ink by default, overridable via the MERMAID_INK_SERVER env
+# var understood by mermaid-py itself) rather than spawning a local Node.js
+# subprocess. It can still hang or fail when that service is unreachable
+# (no network egress, DNS/firewall issues, or an outage). Enabled by default;
 # set MERMAID_VALIDATE=0 to disable.
 _MERMAID_PY_BROKEN = os.environ.get("MERMAID_VALIDATE", "1") == "0"
 _MERMAID_PY_PROBED = True  # Skip probing — rely on env var

pyproject.toml

@@ -64,7 +64,11 @@ dependencies = [
 ]
 
 [external]
-# Node.js is required for mermaid-py which validates mermaid diagrams in generated documentation
+# NOTE: mermaid-py (>=0.8.0, the version pinned below) validates diagrams via
+# an HTTP call to a remote rendering service (mermaid.ink by default), not a
+# local Node.js process -- this nodejs requirement may no longer be needed for
+# that purpose specifically; kept as-is pending confirmation it isn't used
+# elsewhere.
 build-requires = [
     { name = "nodejs", version = ">=14.0.0" }
 ]