Internal deployment details remain in git history (AWS account id, Harmony/Bindle URLs)

## Problem

`docs/internal-deployment.md` has been **deleted from HEAD** (commit `be777a3`), but it remains
reachable in git history and is already published on this repo, so deletion alone does not unpublish it.

Content that was exposed:

- a real AWS account id (all stages shared it)
- Brazil pipeline deployment-group ids
- an internal Harmony app URL (`*.a2z.com`)
- a `code.amazon.com` package link
- a Bindle (access-control) resource URL

## Assessment

None of these are credentials, and the internal URLs are unreachable without corporate auth. The
account id is the main residual: it is an identifier useful for targeting, not a secret by itself.

## Options

1. Accept the residual exposure and rely on the HEAD deletion (lowest effort).
2. Rewrite history (`git filter-repo`) and force-push, plus rotate/redact anything considered
sensitive. This breaks existing clones and forks.

Needs an owner decision — deliberately **not** actioned unilaterally.

Found by a pre-release security audit.

Review the deletion of docs/internal-deployment.md in commit be777a3 and the exposed AWS, Harmony, code.amazon.com, and Bindle details. Then assess the stated git filter-repo option and its impact on clones and forks. Done requires an owner decision to accept the residual exposure or approve history rewriting and any required redaction or rotation.

Written by the indexing model from the issue text.