feat: add exact glossary and reverse transitive deps

[srobinson]

Summary

• add fmm glossary --exact and MCP exact to match full export names only
• add fmm deps --reverse --transitive and MCP reverse closure output with reverse_deps_count
• cover exact glossary, reverse closure cycles, JSON output, MCP schema, and CLI flag contracts

Verification

• just check
• cargo test -p fmm-core build_glossary_exact_matches_only_full_export_name -- --nocapture
• cargo test -p fmm-core reverse_dependency_closure -- --nocapture
• cargo test -p fmm --test cli_glossary -- --nocapture
• cargo test -p fmm --test cli_deps -- --nocapture
• cargo test -p fmm --test mcp_tools -- --nocapture
• cargo test -p fmm --test cli_flags tools_toml_cli_flags_are_exposed_by_clap_commands -- --nocapture
• cargo run -q -p fmm -- glossary Manifest --exact --mode all --limit 20
• cargo run -q -p fmm -- deps crates/fmm-core/src/manifest/mod.rs --reverse --transitive