Fix Windows compatibility and Telegram streaming edge cases

[liuh886]

Summary

This PR collects small Windows/runtime compatibility fixes found while dogfooding on Windows:

• provider tests now pin platform assumptions where command shape differs on Windows
• MIME/file tag fallback behavior is deterministic on Windows
• Windows PID liveness and NVM service paths are normalized
• Matrix media tests patch the module-level DownloadError
• Telegram streaming no longer duplicates already-sent content when an HTML split overflow happens
• Dockerized Claude on Windows keeps stdin open so stdin-fed prompts reach the CLI

Most visible on

• Windows developer/test machines
• Windows service installs using NVM-managed Node paths
• Telegram streaming replies that cross Telegram's message length limit
• Dockerized Claude runs on Windows, where the prompt is intentionally sent via stdin

Fix

• Stabilize platform-sensitive provider tests.
• Add deterministic MIME/image fallbacks in file tag handling.
• Improve PID liveness checks and service path normalization on Windows.
• Adjust Telegram streaming overflow handling so unsealed raw/tool state is flushed before sealing and continuation.
• Pass interactive=_IS_WINDOWS to Claude's Docker wrapper for both normal and streaming calls.

Behaviour

• No behavior change on non-Windows Claude host runs.
• Dockerized Claude receives the same prompt payload as host Claude on Windows; stdin is simply kept open through docker exec -i.
• Telegram streaming still edits/splits normally; the change only prevents already-rendered content from being re-rendered into continuation messages after overflow.
• MIME/path changes are deterministic fallbacks for platform differences.

Tests

• pytest tests/cli/test_claude_provider.py tests/cli/test_codex_provider.py tests/cli/test_providers.py tests/cli/test_auth.py tests/messenger/telegram/test_sender.py tests/messenger/telegram/test_edit_streaming.py tests/files/test_tags.py tests/infra/test_pidlock.py tests/infra/test_service_linux.py tests/infra/test_service_macos.py tests/messenger/matrix/test_media.py -q -> 392 passed
• ruff check ductor_bot/cli/claude_provider.py tests/cli/test_claude_provider.py tests/cli/test_providers.py