[gabrielbmoro]

Summary

Adds baseline support so a developer can adopt EagleEye step by step on a
codebase that already has architecture violations.

A baseline records the violations that exist today. Future runs suppress the
known violations and fail only on new ones — letting a team freeze legacy
debt and block regressions from day one.

How it works

State	dart run eagle_eye:main	dart run eagle_eye:main --baseline
No baseline file	all violations fail (unchanged)	writes baseline, exit 0
Baseline exists, no new violations	success + suppressed count, exit 0	overwrites baseline, exit 0
Baseline exists, new violations	prints new violations only, exit 1	overwrites baseline, exit 0
Baseline exists, stale entries	warns and keeps entries	prunes on write
Malformed baseline	prints error, exit 1	prints error, exit 1

• --baseline is aliased by --update-baseline.
• Baseline file: eagle_eye_baseline.json at the project root (committed).
• Identity: filePath + ruleType + importUri — line/column independent, so
  shifting code around does not resurface known violations.

Changes by layer

• lib/model/: baseline_entry.dart, eagle_eye_baseline.dart,
  exceptions/invalid_baseline_exception.dart
• lib/analyzer/: baseline_filter.dart (BaselineFilter / BaselineResult)
• lib/data/: read/write + JSON via FileHelper, JsonConverter,
  EagleEyeRepository
• lib/eagle_eye_launcher.dart: launchEagleEye({bool updateBaseline})
• bin/main.dart: parses --baseline / --update-baseline
• lib/util/logger_helper.dart: added printInfo
• Docs: README.md, doc/1-getting-started.md, SETUP_PROMPT.md,
  CHANGELOG.md; version bumped to 2.1.0

Tests

New unit tests (model + analyzer):
test/model/baseline_entry_test.dart,
test/model/eagle_eye_baseline_test.dart,
test/analyzer/baseline_filter_test.dart.

Also verified end-to-end in a throwaway project: generate → suppress →
new-only failure → stale warning → prune → malformed handling.

dart analyze   # No issues found!
dart test      # 38 tests passed