feat: add agent @ mentions support in composer #47

Job	Run time
test-js	1m 51s
Rust tests (macOS)	1m 5s
lint	28s
Rust tests (Linux)	2m 7s
Rust tests (Windows)	12m 4s
typecheck	33s
Tauri build (${{ matrix.platform.name }})	-1s
	18m 7s

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