Config file (.dryrc) with ignore globs and per-path threshold/minNodes overrides #23

Problem

Options.parse (src/Options.ts L73) is CLI-only, and the only path filtering is .gitignore (TypeScriptDuplicateFinder.gitignoreMatcher). Consequences:

• No persisted, repo-checked-in ignore globs independent of .gitignore.
• One global threshold/minNodes/minLines for the whole scan — you can't run tests/** looser than src/**, even though test arrange-blocks are a known noise source (≈half the clusters on the abholer run).

Proposed change

Load a config file (.dryrc / dry.config.json) and merge it under CLI precedence:

1. In Options (or a small loader feeding Options.from), read the config from cwd; CLI flags override config, config overrides Options.defaults().
2. Support ignore: string[] globs applied in addition to .gitignore in typeScriptFiles (reuse the existing ignore dependency).
3. Support overrides: [{ paths: glob, threshold?, minNodes?, minLines? }]. Plumb per-path config into clustersFor/matchingPairs (FileScanner is already per-file, so per-file threshold/minNodes is tractable; document the rule for a pair spanning two override scopes — e.g. use the stricter of the two).

Acceptance

• A config setting minNodes: 30 for tests/** and 20 for src/** produces the expected per-tree filtering in a single run.
• ignore globs exclude matching files without touching .gitignore.
• CLI flags still override config values.

Related

The umbrella config surface for the false-positive-reduction set; per-path excludeKinds/minDistinctKinds from the sibling issues can ride on the same overrides mechanism.