Honor minimum community size in architecture reports

[forhappy]

Summary

• make the existing min_community_size report option filter detailed architecture communities
• retain singleton and thin-community nodes, edges, IDs, and assignments in the underlying graph
• preserve raw graph totals and disclose filtered communities through typed omission counts
• document that --min-community-size=1 restores singleton presentation

Evidence

Graphify does not delete singleton communities: it assigns each isolate to a one-node community, then omits communities below its default size threshold of 3 only from detailed reports. A synthetic execution confirmed all nodes remained assigned while thin communities were disclosed as omitted.

A real FastAPI graph measurement found 268 singleton communities, all with degree zero. It also found exact edges in some two-node communities, which demonstrates why small communities must remain queryable rather than being removed from graph.json.

Compatibility

This is a presentation-layer change using an existing option. It does not change graph schema, graph publication, community identity, query behavior, viewer data, or version numbers. Callers that need the previous full directory can set min_community_size to 1.

Verification

• cargo fmt --all -- --check
• cargo test -p compass-output --locked
• cargo clippy -p compass-output --all-targets --all-features --locked -- -D warnings
• cargo clippy --workspace --lib --bins --locked -- -D warnings
• cargo test --workspace --lib --bins --locked
• ./scripts/qualify_code_graph_v1.sh --fixtures-only
• sh scripts/check_product_boundary.sh