feat: implement missing step definitions for BDD tests

- Added step definitions for sections management feature
- Implemented systemIsReady(), iHaveBasicResumeInCity()
- Added resumeHasFollowingSections(), resumeHasFilledSections()
- Implemented iDeleteSection(), resumeShouldContainSection()
- Added iExportResumeToTextFormat(), textShouldContainAllSections()
- Fixed duplicate step definition warnings
- Improved test coverage for Russian language scenarios

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: stden