Add 3.2.0 release notes

[kmcginnes]

Description

Prepares the 3.2.0 release notes and captures a writing rule they follow.

Two commits:

1. Add guidance against em dashes and semicolons in user docs — recovers a rule for docs/agents/documentation.md (avoid em dashes and semicolons in user-facing docs).
2. Add 3.2.0 release notes — a new Changelog.md section in the established style: a marketing intro, feature sections (Styling, Reliable Across Multiple Tabs, Bug Fixes, Schema View), New Contributors, and the full "All Changes" list of every PR since v3.1.0 with author attribution.

Validation

• Prose reviewed against docs/agents/documentation.md (minimal jargon, reader's perspective, no em dashes or semicolons in the new section).
• Terminology aligned with CONTEXT.md (Graph View, Schema View, Active Connection, Styles).
• Feature and contributor claims verified against the merged PR descriptions; new contributors (@1wos, @arnavnagzirkar) confirmed as first-time.

Related Issues

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary.