feat: add MCP Apps extension substrate #769

Job	Run time
Supply-chain vet	2m 15s
Rust fmt	33s
Dependency policy	3m 51s
Rust clippy	33s
License check (workspace)	3m 55s
Rust test (ubuntu-latest)	2m 21s
Build wheels (macos-latest)	49s
Documentation	29s
Rust test (macos-latest)	3m 45s
Build wheels (ubuntu-latest)	53s
Rust build (ubuntu-latest)	2m 41s
Rust build (macos-latest)	1m 33s
Rust test (Redis-backed paths)	41s
Benchmarks (build check only)	4m 28s
Coverage	3m 56s
Resolve Rust Python release matrix	0s
Release wheels (${{ matrix.platform }})	0s
Release sdist	0s
Publish Rust Python packages	0s
	32m 43s

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