feature: add --no-gitignore flag

[11philip22]

What

Add a new acb compile --no-gitignore flag to disable .gitignore filtering during source discovery.

By default, acb compile respects .gitignore, which can unintentionally hide large parts of a codebase from ingestion. This is especially common in reverse engineering workflows where decompiled sources are intentionally kept out of version control.

With --no-gitignore, users can compile the full source tree (including ignored paths) without changing repository ignore rules.

Why this is useful for reverse engineering

In RE projects, directories like decompiled/ or JADX output are often ignored to avoid polluting git history. That is good for versioning hygiene, but bad for analysis coverage when compiling semantic graphs.
This flag allows users to:

• keep decompiled output excluded from git tracking
• still include that output in .acb compilation
• avoid temporary .gitignore edits or moving directories around

Type

• Bug fix
• New feature
• MCP tool
• Documentation

Testing

• Tests added/updated
• All tests pass
• Lints pass

Notes on testing

• Added/updated tests for parser behavior and CLI integration around --no-gitignore.
• Targeted suites for parsing + CLI pass.