feat(opt): three efficiency levers for NL→SQL workflow

Lever 1: Join-graph via FK logics in annotations + suggest-fks command
  - TableAnnotation.foreign_keys field stores curated logical FKs (DWH has no FK constraints)
  - tht schema suggest-fks: mine from approved SQL, heuristics (time_key → dim_time),
    same-name discovery + explicit --assume flag for multi-owner PKs
  - mschema renders 【Foreign keys】 section populated; validation in merge.py
  - SKILL.md F4 now reads FKs from mschema-text, no custom data_time_key logic

Lever 2: Context-pack consolidation at kickoff (tht search pack)
  - Single embedding of question, reused for schema + evidence + solved searches
  - One command: tht search pack <question> --session <id> → retrieval_pack.md
  - Graceful degradation when Ollama/vector store unreachable (exit 0, empty sections)
  - SKILL.md F1 prescribes as first call; reduces model thinking turns via pre-retrieval

Lever 3: Phase-summary recap v2 auto-construction from session ledger
  - tht session show --json includes full decisions ledger
  - tht phase meta --json exports 'emits' (substantive decision types per phase)
  - Gate appends deterministic 【Decisioni registrate in questa fase】 section (appendLedgerSection)
  - Model authors only summary + checks; recap table comes from persisted state (exact by construction)
  - SKILL.md Disciplina 6: brief model output, gate fills the rest

Tests: 358 Python (including 10 FK + 3 pack + 1 session-ledger tests) + 111 JS gate tests, all pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

harness/tests/test_session_show_decisions.py

@@ -0,0 +1,34 @@
+import json
+
+from typer.testing import CliRunner
+
+from tht.cli import app
+
+
+def test_session_show_json_includes_ledger(tmp_path):
+    sid = "2026-01-01-000000-test"
+    sdir = tmp_path / "sessions" / sid
+    sdir.mkdir(parents=True)
+    (sdir / "session_manifest.yaml").write_text(
+        f"id: {sid}\nquestion: q\ndatabase: d\nschema: s\n"
+        "created_at: 2026-01-01T00:00:00+00:00\nstatus: open\n"
+    )
+    (sdir / "review_decisions.jsonl").write_text(
+        '{"seq": 1, "ts": "2026-01-01T00:01:00+00:00", "type": "concept_clarified", '
+        '"subject": "ablazione", "detail": "solo transcatetere", '
+        '"rationale": "scelta reviewer", "phase": 1}\n'
+    )
+    cfg = tmp_path / "workspace.yaml"
+    cfg.write_text(
+        "database: {database: d, schema: s, user: u, password: p, transport: direct}\n"
+        f"paths: {{artifacts: {tmp_path/'artifacts'}, indexes: {tmp_path/'i'}, "
+        f"sessions: {tmp_path/'sessions'}}}\n"
+    )
+    res = CliRunner().invoke(app, ["session", "show", sid, "--json", "-c", str(cfg)])
+    assert res.exit_code == 0, res.output
+    data = json.loads(res.output)
+    assert len(data["decisions"]) == 1
+    d = data["decisions"][0]
+    assert d["type"] == "concept_clarified"
+    assert d["subject"] == "ablazione"
+    assert d["detail"] == "solo transcatetere"