[scan].exclude and [lint].exclude are separate, are not regexes, and dead patterns are not reported #9

Summary

lint ignores [scan].exclude, and exclude patterns are literal prefixes or substrings, not regexes. A pattern that matches no files is silently accepted.

Steps to reproduce

1. In a project with openshell-annotate.toml:

   [scan]
   exclude = ["packages/cli/"]

2. Run openshell-annotate lint .: findings from packages/cli still appear (context7: 26 warnings until the same list was added under [lint]).
3. Use exclude = ["^packages/(admin-mcp|cli)/"]: it silently matches nothing (the README says patterns anchor at the repo root, otherwise they are a substring, so this is a literal string).

Expected

• One shared exclude list: lint inherits [scan].exclude (with [lint].exclude adding to it).
• A warning when an exclude pattern matches zero files.
• Documentation that patterns are not regexes (and the exact matching rule).

Actual

Separate lists, no warning, regex-looking patterns silently match nothing.

Found while testing five real projects (see the local candidate report). Numbered #3 in that report.