v2.2.6 - Enforce branch routing between main and develop

Added

• validation for the correct pull request base branch to protect the flow between main and develop
• automated tests covering valid and invalid branch routing scenarios

Changed

• check-branch now accepts --target to validate the PR base branch
• Branch Policy workflow now validates both the branch name and the PR target branch
• docs, README, contributing guide, and PR template now explain the correct routing between develop and main

Verification

• python -m rede_neural_do_zero verify --build-package
• 92 passed, 38 subtests passed
• branch-policy focused tests passed
• CLI check-branch --target passed locally