test(ppc): identity_op off in the golden generator, with the reason

The shifts clippy objects to are the point. These are instruction ENCODERS:
every field is written at its ISA position, so `(((vb >> 5) & 0x3) << 0)`
sits in a column with << 11, << 16, << 21 and reads straight against the
manual's field table, and a trailing `| 0` says 'the low field is zero
here', which is information.

Reduced to what clippy wants, the encodings stop being checkable by eye
against the ISA -- and eye-checkability is all a golden GENERATOR has. There
is nothing else to verify it against.

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

crates/sylpheed-ppc/tests/disasm_goldens.rs

@@ -1,3 +1,13 @@
+// 🔴 `identity_op` IS OFF FOR THIS FILE, and the shifts it objects to are the
+// point. These are instruction ENCODERS: every field is written at its ISA
+// position, so `(((vb >> 5) & 0x3) << 0)` sits in a column with `<< 11`,
+// `<< 16`, `<< 21` and reads straight against the manual's field table. The
+// trailing `| 0` on a fixed-form word says "the low field is zero here",
+// which is information. Reduced to what clippy wants, the encodings stop
+// being checkable by eye against the ISA, and eye-checkability is the only
+// thing a golden generator has -- there is nothing else to verify it against.
+#![allow(clippy::identity_op)]
+
 //! Assert-based goldens for the PPC disassembler.
 //!
 //! Each test owns an inline list of `(raw, addr, label)` cases. On a