fix(infra): standardize repo scripts on uv run

[lucasbsimao]

Summary

This change standardizes repository-level bootstrap and quality entrypoints to execute through uv run instead of invoking python3 directly.
It also adds a dedicated /create-pr workflow so pull requests can be generated with the repository-required title and body structure.
The result is more consistent local execution for contributors and less drift between documented Python tooling and the commands exposed by the repo.

Release metadata

Release note (PT-BR):
Padroniza a execução de scripts do repositório com uv run e adiciona um fluxo guiado para criação de PRs.

Release note (EN):
Standardizes repository script execution with uv run and adds a guided workflow for creating PRs.

Release highlights (PT-BR, bullets with |):
| Atualiza alvos do Makefile e scripts públicos para usar uv run
| Adiciona workflow /create-pr com conformidade ao template e rotulagem automática

Release highlights (EN, bullets with |):
| Updates Makefile targets and public scripts to use uv run
| Adds a /create-pr workflow aligned with the PR template and auto-labeling

Included pattern IDs (comma-separated, or none):
none

Technical changes (PT-BR, bullets with |):
| Substitui invocações diretas de python3 por uv run python nos entrypoints afetados
| Adiciona .python-version com Python 3.12 para alinhar o ambiente local

Technical changes (EN, bullets with |):
| Replaces direct python3 invocations with uv run python in affected entrypoints
| Adds .python-version with Python 3.12 to align the local runtime

Change type (choose one release label from taxonomy):

• release:major
• release:feature
• release:patterns
• release:api
• release:data
• release:privacy
• release:fix
• release:docs
• release:infra
• release:security

Breaking change?

• No
• Yes (describe migration/impact in summary)

Validation

• Local tests/checks passed for impacted scope
• CI and Security checks are green
• Exactly one release label is set on this PR

Public safety and compliance checklist

• No personal identifier exposure was introduced
• PUBLIC_MODE behavior was reviewed (if relevant)
• Public boundary gate is green
• Public endpoints and demo data contain no personal data fields
• Legal/policy docs were reviewed for scope-impacting changes
• Snapshot boundary remains compliant with docs/release/public_boundary_matrix.csv

Risk and rollback

The main risk is uncovering environments that still rely on calling python3 directly instead of the project-managed uv runtime.
Rollback is straightforward: revert this branch or restore the previous python3 invocations in the Makefile and public bootstrap scripts, then recreate the PR without the workflow addition.

[brunoclz]

Maintainer triage on March 8, 2026: refused for merge in this cycle and kept open.

Blockers:

• The PR touches top-level scripts/** and contributor workflow files, outside the allowed exception policy for this pass.
• The branch is already behind main.
• No release label is currently applied on the PR.

Required next step: narrow this to a minimal safe change or re-open it in a broader infra review cycle after rebasing.