[UroojFatima-052]

Refs #415

Phase 2: removes skillware.core.config and skillware.core.mail_config from [[tool.mypy.overrides]] and fixes the 4 errors that surfaced. Typing only, no behavior change.

Changes

• mail_config.py (validate_addressbook_data): if has_email and isinstance(emails, list):. has_email already checks the type, but mypy can't narrow through a separate bool, so the check is repeated inline. Same runtime behavior.
• mail_config.py (clear_mail_signature_settings): document = dict(_read_yaml(target)). _read_yaml returns a read-only Mapping, but the function edits it (pop, item assignment). Same pattern save_global_presentation_theme already uses.
• config.py (_merge_layers): pass a list to merge_chain_layers instead of a generator, to match its Sequence signature. I fixed the call site rather than widening merge_chain_layers itself, since chains_config.py is outside this phase.
• pyproject.toml: both modules dropped from the overrides list.
• CHANGELOG.md: Unreleased entry.

Verification

• mypy skillware: Success, no issues in 24 files
• black --check / flake8 on both files: clean
• pytest tests: 588 passed. The only failures are semantic_web_proxy, which fails locally on a missing lxml_html_clean package and is unrelated to this change.

Remaining overrides after this: skillware.cli and skillware.core.loader (Phase 3 onwards).

[rosspeili]

LGTM @UroojFatima-052, merging this one as is. Thanks for this. <3