feat(config): excluded_branch_patterns

[jbspeakr]

Summary
I want to be able to not only exclude absolut branch names from auto-review using excluded_branches but also by name prefixes/ patterns.

Motivation
Being able to exclude particular branch patterns (e.g. agent-driven worktree-agent-* branches that eventually get merged in a proper feature branch) would help avoiding unnecessary/ duplicate reviews.

Proposed Solution
Introduce a excluded_branch_patterns config similar to excluded_commit_patterns .