config: remove the never-read PlatformConfig.pip_value (rule 8)

Every live reader of a pip value goes through PAIR_INFO[...]["pip_value"]
(signal_aggregator, gpu_backtest, diagnose_filters) or TradeSetup.pip_value;
no code read the PlatformConfig field. The three PlatformConfig(...)
constructions that passed it (gpu_backtest x2, diagnose_filters) and the
inline construction in the factory-equivalence test drop the kwarg. Neither
config fingerprint hashes the field, so logged fingerprints are unchanged.
The removed-field test now also asserts pip_value stays gone.

Parity: 12-month M5 and H1 books regenerated byte-identical
(md5 a28fed4becd056466c26d6a947e1a0e5 / d20405ef64f069770c258bb9bed1ac90).
Suite: 461 passed, 0 failed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0156YhogLytzj9P2iH1skGbL

test_all.py

@@ -2072,7 +2072,6 @@ def _():
         inline_cfg = PlatformConfig(
             symbol=XAUUSD,
             display_name="XAU/USD",
-            pip_value=0.10,
             primary_timeframe=tf,
             confirmation_timeframes=ctfs,
         )
@@ -3259,10 +3258,12 @@ def _():
         assert deepseek_api_key(AppConfig()) == ""
 
 
-@test("config.py: hardcoded twelve_data_api_key field is gone")
+@test("config.py: removed PlatformConfig fields stay gone (twelve_data_api_key, pip_value)")
 def _():
     assert not hasattr(PlatformConfig(), "twelve_data_api_key"), \
         "credentials must not live in committed source"
+    # pip value comes from PAIR_INFO; the config field was never read (2026-09-06).
+    assert not hasattr(PlatformConfig(), "pip_value")
 
 
 @test("telegram_bot: credentials, quality, pairs, loops from app_config")