Record empty stop hook payloads

[Siddhant-K-code]

Summary

• Record stop hook markers even when the provider does not include assistant text.
• Preserve stop/session-end metadata such as stop_reason, reason, transcript_path, cwd, and hook_event_name.
• Generate Copilot's documented Stop hook and add SessionEnd for Copilot CLI.
• Add an explicit Cursor stop hook alongside afterAgentResponse.
• Add aliases for camelCase/PascalCase provider event names.
• Bump patch version to 0.80.1.

Context

Provider stop hooks are not guaranteed to carry assistant text. Copilot's documented stop payload is metadata-oriented (transcript_path, stop_reason), so the previous handle_stop early return made real emitted stop hooks look like they never fired. This does not force providers to emit stop hooks for every UI action, but it records the hook whenever the provider sends it.

Verification

• python3 -m pytest tests/test_hooks.py tests/test_copilot_hooks.py tests/test_cursor_hooks.py tests/test_codex_hooks.py tests/test_gemini_hooks.py -q -> 51 passed
• python3 -m compileall -q src/agent_trace && git diff --check
• python3 -m pytest tests/ -q -> 1604 passed
• python3 -m agent_trace.cli --version -> agent-strace 0.80.1