docs: reflect normalization fixes, detector cleanup and CLI overrides

- README: remove stale detector_response.py tree entry and the
  detector-models highlight (module removed); document per-branch
  measured transition endpoints from paceENSDF and JSON-flow CLI
  override semantics
- TODO: drop the DEFAULT_JSON_SCHEMA detector-keys clause (removed)
- data/custom_input_example.json: strip dead detector_* keys

TODO.md

@@ -32,7 +32,7 @@ beta_spectrum/              ← theory-only core
 │   ├── screening.py
 │   ├── exchange.py
 │   ├── radiative.py
-│   └── detector_response.py   ← stays here (part of theory)
+│   └── (detector_response.py — removed; restore-or-delete pending below)
 └── nuclear_data.py         ← paceENSDF integration
 
 exp_data/                   ← experimental data handling
@@ -102,9 +102,10 @@ output/                     ← output, visualization, CSV export
 - [x] README updated with new architecture diagram and Quick Start examples
 - [x] Version bumped to 0.4.0
 - [ ] Decide: restore or delete the `detector_response` module — it was removed from
-  `beta_spectrum/components/` together with its tests, but `fitter/model.py` keeps a
-  duck-typed optional hook and `DEFAULT_JSON_SCHEMA` keeps the detector keys;
-  restore from git history (commits up to `5f99566`) if convolution is needed again
+  `beta_spectrum/components/` together with its tests; `fitter/model.py` keeps a
+  duck-typed optional hook only (`DEFAULT_JSON_SCHEMA` detector keys and the CLI
+  dry-run detector line were removed with audit cleanup).
+  Restore from git history (commits up to `5f99566`) if convolution is needed again
 
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