Add analyzer fixture tests for unsupported, unknown, and ambiguous projects

[renvoxit]

Current status

This issue is still relevant.

The analyzer is no longer fully hardcoded and can detect several basic project types, but it is still intentionally basic. Unsupported, unknown, empty, and ambiguous repository cases should be documented by tests before the analyzer becomes smarter.

This is useful preparation for a future smarter analyzer stage, but it should not block the Frontend MVP Shell.

Goal

Add tests for analyzer behavior when project type cannot be detected cleanly.

Scope

Cover cases like:

• empty project
• project with unrelated files
• project without recognized config files
• unsupported project type
• ambiguous project with multiple indicators, if current behavior is defined
• project with partial config files that should not be misdetected

Out of scope

• Do not improve project detection logic.
• Do not add new project types.
• Do not modify template rendering.
• Do not touch Docker build/run.
• Do not block frontend shell work.

Acceptance criteria

• Analyzer behavior for unsupported projects is documented by tests.
• Ambiguous behavior is either tested or explicitly documented as undefined.
• Tests use virtual/in-memory fixtures if that is the current preferred pattern.
• Existing analyzer and backend tests still pass.