fix: remove mutable default arguments in SemanticRouter (follow-up to #700)

[harshadkhetpal]

Summary

Follow-up to #700 (merged last month): extensions/router/semantic.py has the same shared-mutable-default pattern (ruff B006) in code that wasn't covered there:

• SemanticRouter.__init__(connection_kwargs: dict[str, Any] = {})
• get_route_references(reference_ids: list[str] = [], keys: list[str] = [])
• delete_route_references(reference_ids: list[str] = [], keys: list[str] = [])

All five become | None = None. Unlike #700, no normalization statements are needed — I audited every use: __init__ already forwards connection_kwargs or None, and both methods only touch reference_ids/keys behind truthiness guards (if reference_ids:, if not keys: with reassignment before any iteration). So None behaves identically to the old shared {}/[] at every site, and the diff is just the five signature lines.

Testing

python -m py_compile passes; ruff check --select B006 on the file goes from 5 errors to clean.

🤖 Generated with Claude Code

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Note

Low Risk
Signature-only fix for shared mutable defaults; call sites already handle None like empty dict/list.

Overview
Follow-up to #700: fixes ruff B006 mutable default arguments on SemanticRouter in semantic.py.

__init__ now takes connection_kwargs as dict[str, Any] | None = None instead of = {}. get_route_references and delete_route_references use reference_ids and keys as list[str] | None = None instead of = [].

No new if x is None: x = ... normalization—the existing connection_kwargs or None forward and truthiness checks on reference_ids/keys already treat omitted args the same as empty collections.

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