refactor: move dispatch into per-subcommand modules

[shadowhand]

Summary

Stacked on #82.

Each top-level subcommand module now exposes a dispatch function that owns the inner match for its *Commands enum. main.rs::run becomes a thin shell that maps Commands variants to those, replacing the deeply-nested ~230-line ladder with a flat 11-arm match.

main.rs: 464 → 302 lines

// Before: each variant had its own multi-line dispatch
Commands::Clinicians(clinician_args) => {
    let ctx = build_ctx(...)?;
    match clinician_args.command {
        CliniciansCommands::Assign(args) => {
            commands::clinicians::assign(&ctx, &args.target, &args.team, out).await?;
        }
        CliniciansCommands::Grant(args) => {
            commands::clinicians::grant(&ctx, &args.target, &args.role, out).await?;
        }
        // ... 6 more variants
    }
}

// After
Commands::Clinicians(args) => {
    let ctx = build_ctx(&config, profile_override.as_deref(), auth_override.as_deref(), config_dir)?;
    commands::clinicians::dispatch(args, &ctx, out).await?;
}

Dispatcher signatures

• Most: (args, &AppContext, &Output) — auth, api, artifacts, clinicians, roles, teams, workspaces
• update::dispatch(out) — no args, no ctx
• skills::dispatch(args, out) — args, no ctx
• config::dispatch(args, &mut Config, &cfg_path, &config_dir, profile_override, out) — needs Config, not AppContext

build_ctx still gets called per-arm because the four dispatcher signatures need slightly different argument shapes; a forced-uniform signature would require awkward AppContext-or-Config plumbing for no win.

Stack ahead

8. Extract Stage + slug to a domain module
9. CI hardening

Test plan

• cargo fmt --check clean
• cargo clippy --all-targets — same 11 pre-existing warnings, none from changes
• cargo test — 288 pass total (270 lib + 7 bin + 11 integration), unchanged

https://claude.ai/code/session_012fVDyKBysF1ERtvVuEAw2Y

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Generated by Claude Code

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.