Cardano Updates

When compiling caseInteger in non-BuiltinCasing mode (SumsOfProducts),
the fallback used PlutusTx.List.!! which built a linked list of branches
at runtime and indexed into it with a Y-combinator. This caused a 3-5x
execution cost regression for unsafeFromBuiltinData on multi-constructor
types (reported by the Hydra team, see #7691).

Replace the fallback with mkEqualsIntegerChain, which generates a flat
chain of equalsInteger/ifThenElse comparisons in PIR. This produces UPLC
equivalent to the pre-caseInteger code path with no runtime allocation.

See Note [caseInteger non-BuiltinCasing fallback] in Expr.hs.

Temporarily set `if False` in unsafeFromDataClause to bypass caseInteger
and generate golden files from the old equalsInteger/ifThenElse code path.
These serve as the equivalence target for the Expr.hs fix.

Adds a minimal test that compiles unsafeFromBuiltinData on a 3-constructor
type in the default SumsOfProducts mode (no BuiltinCasing pragma).
This captures the caseInteger fallback regression for comparison.

The `input-output-hk/plutus-apps` repository has been archived,
causing the Broken Links CI workflow to fail.

The `input-output-hk/plutus-apps` repository has been archived,
causing the Broken Links CI workflow to fail.

* Add Flat encoding test coverage across all packages

Pay down test coverage debt for Flat serialization instances.
This ensures encoding stability is verified by tests before
we attempt to fix the Generic derivation bug in a follow-up PR.

Adds roundtrip and stable byte encoding tests for:
- Flat library types (Maybe, Either, NonEmpty, Complex, Ratio,
  Set, Tree, Map, Seq, DList, Filler, PreAligned, and
  monoid/semigroup wrappers)
- TPLC types (Version, Name, Kind, DeBruijn, NamedDeBruijn,
  SrcSpan, SrcSpans, DefaultFun, DefaultUni, and all newtype
  wrappers including TyName, Unique, TyDeBruijn, etc.)
- PIR types (Recursivity, Strictness)
- UPLC types (Binder variants, FakeNamedDeBruijn, minimal
  Program encoding)
- Value types (K encodes as ByteString, Quantity as Integer)

Also adds a standalone encoding generator executable
(cabal run flat-encoding-generator) for reproducing expected
byte constants.

* fix(flat): address PR review feedback on encoding tests

Rename testNewEncodings to testEncodingStability for clarity.
Fix plutus-core ^>=1.59 version bound to ^>=1.60. Remove
unnecessary -Wno-* flags and unused text dependency from
flat-encoding-generator. Improve executable comment with
golden testing context and Wikipedia reference.

* Replace flat-encoding-generator with golden tests

The encoding stability tests now use tasty-golden instead of
hardcoded inline byte sequences. This addresses review feedback
about the generator executable being redundant when --accept
can regenerate golden files directly.

- Convert testEncodingStability (flat/test) to goldenVsStringDiff
- Convert test_flatStaticEncoding (TPLC) to goldenVsStringDiff
- Remove flat-encoding-generator executable
- Add tasty-golden dependency to flat-test

* Rename golden file for consistent naming

Both golden files now use encoding-stability.golden.