chore(security): move instance content behind private boundary

[allenwoods]

Summary

• remove instance-specific operations, landing plans, runtime overrides, E2E runtime evidence, and personal agent state from the public tip;
• neutralize public docs, issue templates, help defaults, routes, examples, and development instructions;
• route branded content, concrete environment facts, runbooks, and evidence to HackForger/synnovator-private-content;
• retain business-neutral platform design specs and relocate reusable E2E templates to docs/testing/e2e/templates/;
• ignore /.remember/ so agent session logs cannot flow back into the public index.

The private migration is already committed and pushed at f1d7322dd92871470233f317ee9b45d382f6d878. Its no-secrets check passes and its landing manifest covers exactly 101 files.

Verification

• immutable pre-push hook: public repository boundary: PASS;
• local full-tree/history boundary scan: PASS;
• 53 complete boundary tests: PASS;
• 24 content publisher transaction/provenance/rollback tests: PASS;
• JSON, YAML, Bash syntax, and git diff --check: PASS;
• earlier focused Go tests for the neutral data-key change passed; subsequent Go edits are comments only (the current shell no longer has a Go toolchain on PATH);
• exact cleanup topology: one commit on the latest default SHA b87b90fe0f2cfefd6a143eee2f033a3da71f54ed.

Production safety

• This PR performs no deployment.
• Never run rsync --delete after merge.
• Never run redeploy.sh for this content-only migration.
• The production landing tree is externally owned and remains on the server.
• The private runtime help override is version-coupled to the new PlatformHTML key and is intentionally excluded from the landing-only release.

Security scope

This PR cleans the current branch tip. It does not erase already-public Git history or stale branch/tag tips, and it does not rotate previously published test credentials. Those require a separately authorized incident-remediation operation (credential revoke/rotation first, then coordinated ref cleanup/history rewrite) and must remain open after this PR merges.