L3 Oral Tradition: PostgreSQL persistence layer for interpretations, minority opinions, teiku

Devarim 17:9 — v'darashta v'higidu lekha et d'var hamishpat.
The inquiry requires that what is found is RECORDED.

- Ecto Repo with graceful degradation (maybe_add_repo, like other engines)
- Migration: interpretations, minority_opinions, teiku_registry tables
  - Append-only enforcement via REVOKE UPDATE/DELETE
  - Includes eish_zarah fields: coupling_trace, grounding_type, challenge_sequence
- Ecto schemas: Interpretation, MinorityOpinion, TeikuRecord
  - Changeset validations: status inclusion, panel_size > 0, grounding_type enum
  - TeikuRecord.resolve_changeset restricts updates to resolved_at/resolution only
- L3.Store bridge module: record, query, count operations
- L3 tests tagged @moduletag :l3, excluded by default (no local PostgreSQL)
  - Enable with: SHORASHIM_L3=1 mix test --include l3
- All 76 existing Elixir tests pass, 195 Prolog tests pass, 33 Haskell tests pass

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vav_pipeline/lib/vav_pipeline/application.ex

@@ -3,6 +3,7 @@ defmodule VavPipeline.Application do
   OTP Application for the Vav Pipeline.
 
   Starts the supervision tree with:
+  - Repo (L3 PostgreSQL — oral tradition persistence)
   - ShabbatTimer (mandatory cessation monitor)
   - ShoreshEnginePort (Erlang Port to Haskell engine, if binary found)
   - TalmudicEngineSocket (Unix socket to Prolog engine)
@@ -26,6 +27,7 @@ defmodule VavPipeline.Application do
       [
         {VavPipeline.ShabbatTimer, []}
       ]
+      |> maybe_add_repo()
       |> maybe_add_shoresh_port(shoresh_binary, shoresh_cwd)
       |> maybe_add_talmudic_socket(talmudic_socket)
 
@@ -33,6 +35,23 @@ defmodule VavPipeline.Application do
     Supervisor.start_link(children, opts)
   end
 
+  defp maybe_add_repo(children) do
+    repo_config = Application.get_env(:vav_pipeline, VavPipeline.Repo)
+
+    cond do
+      is_nil(repo_config) ->
+        Logger.warning("VavPipeline.Repo: no config found — running without L3 persistence")
+        children
+
+      repo_config[:start] == false ->
+        Logger.info("VavPipeline.Repo: start disabled — running without L3 persistence")
+        children
+
+      true ->
+        [VavPipeline.Repo | children]
+    end
+  end
+
   defp maybe_add_shoresh_port(children, binary, cwd) do
     case System.find_executable(binary) do
       nil ->