fix(ci): migrate sonarcloud to org reusable workflow and correct sonarcloud-organization

[williaby]

Problem

• `sonarcloud.yml` has inline steps using `sonarqube-scan-action@884b79409...` (v4.0.0); should delegate to the `python-sonarcloud.yml` org reusable workflow at SHA `6bad2f898be1d387b8424e9deddefa519674cb19`, which uses v7.2.0 and resolves the `/analysis/analyses` 404 bug on new projects
• `sonarcloud-organization` in `ci.yml` is `ByronWilliamsCPA` but should be `williaby` (the actual SonarCloud account name)

Fix

Apply the same changes made in ByronWilliamsCPA/llc-manager#10:

1. Replace inline `sonarcloud.yml` with a thin caller to `python-sonarcloud.yml@6bad2f898be1d387b8424e9deddefa519674cb19` with `skip-if-no-token: true`, `fail-on-quality-gate: false`, `sonar-organization: 'williaby'`
2. Correct `sonarcloud-organization` to `williaby` and set `enable-sonarcloud: false` in `ci.yml` (delegating sonarcloud responsibility to `sonarcloud.yml`)

Reference

• org `.github` PR 43: removed concurrency blocks from reusable callees; upgraded sonarqube-scan-action to v7.2.0
• org `.github` PR 44: documented pull-requests:write relay requirement
• llc-manager PR 10: reference implementation