:Release Notes:
- Added a new Telegram command `/get_hottest <number> [format]` to export the top `N` trends as a CSV or Markdown file.
:Detailed Notes:
- Created `ITrendExporter` interface and concrete `CsvTrendExporter` and `MarkdownTrendExporter` implementations for formatting DTOs.
- Updated `src/bot/handlers.py` to include `command_get_hottest_handler` mapping to `/get_hottest`.
- Used `BufferedInputFile` to stream generated files asynchronously directly to Telegram without disk I/O.
- Fixed unrelated pipeline test failures regarding `EphemeralClient` usage with ChromaDB.
:Testing Performed:
- Implemented TDD with `pytest` for parsing parameters, exporting logic, and handling empty DB scenarios.
- Ran the full test suite (90 tests) which completed successfully.
:QA Notes:
- Fully covered the new handler using `pytest-asyncio` and `aiogram` mocked objects.
:Issues Addressed:
- Resolves request to export high-relevance parsed entries.
Change-Id: I25dd90f1e4491ba298682518d835259bffab4190
