slice 9 cleanup: drop legacy research/loops backend + tables

Retires the legacy research/loops backend after the missions arc
(slices 1-9) fully replaced it. Frontend cutover was 4663348; this
commit finishes the job on the backend + database.

Migration:
  - 0053_drop_legacy_research_loops.sql — drops the 8 legacy tables
    (research_topics, research_topic_agents, research_outcomes,
    research_publish_approvals, loops, loop_agents, loop_orgs,
    loop_teams) and the 3 topology_runs FK columns
    (research_topic_id, loop_id, iteration). parent_run_id stays;
    recursive_exec still uses it.

Files deleted (11):
  - crates/cm-api/src/routes/{research,loops,research_setup,
    research_pipeline,wizard_repo,probe}.rs
  - crates/cm-api/src/research_container.rs
  - crates/cm-db/src/repo/{research_topics,research_outcomes,
    research_publish_approvals,loops}.rs
  - crates/cm-runtime/src/loops.rs
  - crates/cm-api/tests/research_publish_role.rs

Files edited:
  - crates/cm-api/src/lib.rs — dropped 20 legacy route registrations
    (all /api/research/* + /api/loops/* + /webhooks/loops + probe)
    and module decls
  - crates/cm-api/src/topology_worker.rs — deleted legacy dispatch
    (freeze_research_outcome, advance_loop_after_completion,
    continue_initial_burst, maybe_transition_research_topic,
    parse_reorder_rationale, per-topic/loop gateway resolver).
    reap_stuck_runs now keys on mission_id (not topic_id).
    Executor path unconditionally uses ZeroClawDriveExecutor::from_env
    — mission_orchestrator provisions each claw as an agent inside
    the shared runtime via RuntimeProvisioner, so per-team gateway
    resolution is no longer applicable.
  - crates/cm-api/src/routes/topology.rs — deleted container-log SSE
    endpoint (research/loop-specific), dropped loop_id filter and
    iteration field from ListRunsQuery/RunSummary
  - crates/cm-api/src/routes/world.rs — removed
    active_research_topics/active_loops/preseed_repo_paths;
    World SSE no longer emits repo:{topic}/loop:{id} landmark orbs
    (follow-up task #21 tracks adding mission:{id} equivalents)
  - crates/cm-api/src/runtime_provision.rs — removed now-unused
    mint_workspace_service_token
  - crates/cm-db/src/repo/topology_runs.rs — removed 9 legacy
    helpers (research_topic_id lookup, loop_id_for_run,
    iteration_for_run, active_runs_for_research_topic, etc.)
  - crates/cm-db/src/repo/teams.rs — removed 4 dead helpers
    (team_for_loop, team_for_research_topic + setters)
  - crates/cm-api/tests/topology_jobs.rs — removed loop/topic
    tests, dropped enqueue_run_with_topic helper
  - crates/bins/clawmates-server/src/main.rs — removed
    spawn_loop_scheduler call
  - crates/cm-api/src/routes/mod.rs, crates/cm-db/src/repo/mod.rs,
    crates/cm-runtime/src/lib.rs — module decls stripped

sqlx cache: regenerated against post-migration schema
  (71 files changed, ~+70 / -8896 net)

Test/build: SQLX_OFFLINE=true cargo check --workspace clean;
cargo test --workspace --no-run clean.

Follow-up (task #21): World view lost the in-flight-work landmarks
when repo:{topic} / loop:{id} orbs disappeared. Add mission:{id}
orbs as the missions-era replacement.

crates/bins/clawmates-server/src/main.rs

@@ -299,7 +299,6 @@ async fn run() -> Result<(), String> {
     cm_runtime::spawn_drainer(pool.clone(), std::time::Duration::from_secs(10));
     // Loop scheduler: fires cron-triggered loop iterations. Missed windows
     // fire ONCE and skip the backlog (see cm_runtime::loops for details).
-    cm_runtime::spawn_loop_scheduler(pool.clone(), std::time::Duration::from_secs(10));
     // Expiry/retention sweep: expires stale auth/oauth rows and prunes old
     // journal/audit rows hourly so unbounded tables don't accumulate.
     cm_api::cleanup_sweeper::spawn(pool.clone(), std::time::Duration::from_secs(3600));