Simplify boilerplate for learning: stub inference and Postgres write

Removed ort/ndarray/image (ONNX Runtime inference) and sqlx (Postgres audit
write). inference::detect() and the Postgres half of reporter::report() are
now stubs with a comment for what real code goes there. Redis Streams
XREADGROUP loop and the Redis pub/sub alert stay real.

Verified with a clean cargo check --all-targets (0 warnings).

README.md

@@ -2,9 +2,18 @@
 
 Computer-vision failure detection worker for the Continuum print farm
 platform. Consumes camera frame batches pushed onto the Redis Stream
-`stream:camera_frames` (by `continuum-backend`'s `src/queue/`), runs them
-through an ONNX Runtime model, and fast-paths high-confidence failure alerts
-back to Redis and Postgres.
+`stream:camera_frames` (by `continuum-backend`'s `src/queue/`) and reports
+failures.
+
+## This is a learning-stage boilerplate
+
+Real ONNX Runtime inference (the `ort` crate) and the Postgres audit write
+(`sqlx`) are **not** implemented yet — `src/inference/mod.rs` always
+"detects" one fixed example failure, and `src/reporter/mod.rs` only prints
+where the Postgres write would go. The Redis Streams consumer-group loop in
+`main.rs` and the Redis pub/sub alert in `reporter/` are real. This lets the
+whole pipeline (read a frame, "detect", report, ack) run and be understood
+before adding a real model or a SQL database on top.
 
 ## Pipeline
 
@@ -13,24 +22,24 @@ continuum-proxy --(frames)--> continuum-backend --(XADD)--> stream:camera_frames
                                                                     |
                                                           XREADGROUP (this worker)
                                                                     v
-                                                        src/inference (ort session)
+                                                     inference::detect (stub for now)
                                                                     v
-                                                  src/reporter (Redis pub/sub + Postgres INSERT)
-```
-
-## Structure
-
-```
-src/
-  main.rs         Consumer-group loop: XREADGROUP -> decode -> infer -> report -> XACK
-  inference/       Thread-safe ONNX Runtime session wrapper + pre/post-processing
-  reporter/        Alert fan-out: Redis pub/sub for realtime UI, Postgres for audit trail
+                                                 reporter::report (Redis pub/sub — real)
 ```
 
 ## Getting started
 
 ```bash
 cp .env.example .env
-# place an ONNX failure-detection model at ./models/failure-detector.onnx
 cargo run
 ```
+
+## Structure
+
+```
+src/
+  main.rs          Consumer-group loop: XREADGROUP -> detect -> report -> XACK
+  config.rs        Loads settings from environment variables
+  inference/       Detection stub — real ONNX Runtime inference goes here later
+  reporter/        Redis pub/sub alert (real) + a note for the Postgres write (later)
+```