chore(nervous-system): Update changelog for release 2026-08-14

[daniel-wong-dfinity-org-twin]

Update CHANGELOG.md for today's release.

NNS

• 143577
• 143578
• 143579

SNS

[github-actions]

This pull request changes code owned by the Governance team. Therefore, make sure that
you have considered the following (for Governance-owned code):

1. Update unreleased_changelog.md (if there are behavior changes, even if they are
   non-breaking).

2. Are there BREAKING changes?

3. Is a data migration needed?

4. Security review?

How to Satisfy This Automatic Review

1. Go to the bottom of the pull request page.

2. Look for where it says this bot is requesting changes.

3. Click the three dots to the right.

4. Select "Dismiss review".

5. In the text entry box, respond to each of the numbered items in the previous
   section, declare one of the following:

• Done.

• $REASON_WHY_NO_NEED. E.g. for unreleased_changelog.md, "No
  canister behavior changes.", or for item 2, "Existing APIs
  behave as before.".

Brief Guide to "Externally Visible" Changes

"Externally visible behavior change" is very often due to some NEW canister API.

Changes to EXISTING APIs are more likely to be "breaking".

If these changes are breaking, make sure that clients know how to migrate, how to
maintain their continuity of operations.

If your changes are behind a feature flag, then, do NOT add entrie(s) to
unreleased_changelog.md in this PR! But rather, add entrie(s) later, in the PR
that enables these changes in production.

Reference(s)

For a more comprehensive checklist, see here.

GOVERNANCE_CHECKLIST_REMINDER_DEDUP

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to c967d83.

Security Overview

• 🔎 Scanned files: 7 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/f975f1a5-0a47-4a3b-b7f0-a55609e90390?scanId=27a969e6-97ce-4a23-b871-cd37ac019137&codeScanTypes=PrScan&tab=issues

Detected Code Changes

The diff is too large to display a summary of code changes.

[basvandijk]

I guess this 45.8 MB file was added by accident. Could you remove it by force pushing a commit to your PR branch such that your branch doesn't reference a commit with this large file anymore? Otherwise we would be paying for this until eternity.