Add CHANGELOG.md with TNRKit v0.5.0 release notes

[Copilot]

Documents all changes since v0.4.0 in a new CHANGELOG.md, with explicit coverage of every breaking interface change affecting exported symbols.

Breaking Changes

Unified model interface (#149)

All _symmetric model variants removed. Symmetry type is now passed as the first positional argument; no-argument / bare-β calls now return the maximally symmetric tensor by default.

# v0.4.0
classical_ising(β)            # non-symmetric
classical_ising_symmetric(β)  # Z2Irrep

# v0.5.0
classical_ising(Trivial, β)   # non-symmetric
classical_ising(β)            # Z2Irrep (new default)

Removed exports: classical_ising_symmetric, classical_ising_symmetric_3D, classical_ising_triangular_symmetric, classical_potts_symmetric, classical_clock_symmetric, classical_XY_U1_symmetric, classical_XY_O2_symmetric, phi4_real_symmetric, phi4_complex_symmetric.

All model functions now accept a T::Type{<:Number} keyword to control element type.

LoopTNR run! interface (#144)

Six-argument form replaced by LoopParameters struct:

# v0.4.0
run!(scheme, trscheme, truncentanglement, criterion, entanglement_criterion, loop_criterion)

# v0.5.0
run!(scheme, trscheme, criterion, LoopParameters())

The simplified run!(scheme, trscheme, criterion) form still works.

New Methods

• CorrelationHOTRG (CorrelationHOTRG #139) — two-point correlators at distance 2ⁿ via HOTRG
• c3vCTM_honeycomb (Implement c3vCTM on the honeycomb lattice #141) — C3v-symmetric CTMRG for honeycomb lattices

New Exports

• LoopParameters (Nuclear norm regularized LoopTNR #144) — bundles loop optimization config; enables NNR-TNR
• VN_entropy, loop_entropy (Nuclear norm regularized LoopTNR #144) — entanglement entropy utilities for LoopTNR
• classical_ising_honeycomb, ising_βc_honeycomb, f_onsager_honeycomb (Implement c3vCTM on the honeycomb lattice #141)
• classical_XY, XY_βc — unifies classical_XY_U1_symmetric / classical_XY_O2_symmetric

Bugfixes

• 3D HOTRG: wrong twist factors and svd_trunc → eigh_trunc for projectors (Fix twist and use eigh_trunc in 3D HOTRG #145)
• Onesite CTM was broken (Fix onesite CTM #155)
• Symmetric complex φ⁴ tensor construction incorrect (Fix complex phi4 #142); doc/type cleanup (Small Improvement Complex phi4 model #147)

---

🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.