feat(cli): spar emit --format mermaid subcommand (v0.10.x M2)

[avrabe]

Motivation

Mermaid M1 (#220) landed spar-mermaid with emit_flowchart. This PR (M2) exposes it to users via a new spar emit CLI subcommand, completing the user-visible half of the Mermaid flowchart pipeline.

Scope

• CLI only, flowchart only (classDiagram is M3; round-trip tests are M4; per-mode emission is v0.11.0)
• Parallel to spar render (SVG via etch) — not combined with it

Changes

1. crates/spar-cli/Cargo.toml — adds spar-mermaid.workspace = true
2. crates/spar-cli/src/main.rs — dispatch entry "emit", cmd_emit function, parse_category helper, updated print_usage()
3. crates/spar-cli/tests/emit_mermaid.rs — 2 integration tests (happy path + category filter)
4. artifacts/requirements.yaml — REQ-MERMAID-CLI-001
5. artifacts/verification.yaml — TEST-MERMAID-CLI

Example invocations

# Emit full flowchart to stdout
spar emit --root MyPkg::Sys.Impl path/to/file.aadl

# Filter to threads only, limit depth, write to file
spar emit --root MyPkg::Sys.Impl --format mermaid --category thread,processor --max-depth 2 file.aadl > diagram.md

# Suppress connection edges
spar emit --root MyPkg::Sys.Impl --no-connections file.aadl

Sample output (from integration test fixture)

flowchart TD
    TestSys["system: TestSys"]
    app["process: app"]
    cpu["processor: cpu"]
    worker["thread: worker"]

Links

• M1 foundation crate: feat(mermaid): spar-mermaid foundation with flowchart emitter (v0.10.x) #220
• rivet validate passes (99 pre-existing warnings, no new errors)
• cargo test -p spar --test emit_mermaid — 2/2 passing
• cargo clippy -p spar -- -D warnings — clean
• cargo fmt --check — clean

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.7 noreply@anthropic.com