fix(gmail): preserve Cc recipients regardless of header casing

[ZIFeIYUuuuuuu]

Fix Gmail +reply-all dropping Cc recipients when header casing differs

Problem

Gmail header names are case-insensitive, but +reply-all only recognized the exact spelling Cc. Messages returned with CC, cc, or another casing were parsed without any Cc recipients, so the reply omitted people who were copied on the original message.

Minimal reproduction:

1. Reply-all to a message whose Gmail API payload contains a header such as { "name": "CC", "value": "alice@example.com" }.
2. The current parser falls through to _ and leaves ParsedMessageHeaders.cc empty.
3. The generated reply therefore does not include the original Cc recipient.

Root cause

parse_message_headers used a case-sensitive string match for "Cc". RFC 5322 header field names are case-insensitive, and Gmail can return equivalent casing variants.

Changes

• Match the Cc header with eq_ignore_ascii_case("Cc") while preserving existing address-list concatenation and formatting.
• Add a focused regression test covering both CC and cc headers and asserting that both recipients are retained.
• Add the required patch changeset.

Validation

• cargo test -p google-workspace-cli helpers::gmail::tests -- --nocapture (113 passed)
• cargo test -p google-workspace-cli helpers::gmail::tests::test_parse_message_headers_preserves_cc_regardless_of_header_case -- --exact --nocapture (1 passed)
• cargo fmt --all -- --check (passed)
• cargo clippy -p google-workspace-cli -- -D warnings -A clippy::collapsible-match (passed; the allow is for an existing unrelated warning in helpers/script.rs)
• git diff --check (passed)

Other header handling and normal truncation/error behavior are unchanged. This closes #911.

[changeset-bot]

🦋 Changeset detected

Latest commit: d907083

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@googleworkspace/cli	Patch

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[googleworkspace-bot]

/gemini review

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