Split ELF MCP server tool routers

[yvette-carlisle]

Summary

• move elf-mcp into a flat app/server Rust module tree without #[path] module hooks
• split MCP docs and admin tool routers into tools/docs.rs and tools/admin.rs, then aggregate core/docs/admin routers
• update eval tests and active docs/evidence references for the new MCP server paths

Validation

• cargo make fmt-rust
• cargo make check-rust
• cargo make lint-vstyle
• cargo make lint-rust
• cargo make test-rust
• cargo make check-docs
• cargo make check
• git diff --check
• read-only skeptic audit; resolved active evidence path drift before final check