fix(release): preserve single-tag changelog semantics

[levi770]

Summary

• regenerate the current release changelog from the exact unpublished workspace version without duplicating existing sections
• preserve the recursive epistemic behavior notes from the merged implementation and match only the exact originating commit subject
• keep compare links, breaking-change normalization, workflow preparation, documentation, and contract tests aligned with a single tagged release
• include the release/docs generation suites in the existing Python contract CI gate

Relationship

This is stacked on #260 and is the tested replacement for the stale rolling release output in #197. Merge #260 first; this PR does not merge, tag, publish, or close #197 automatically.

Verification

• two consecutive clean public-registry generations with release-plz 0.3.157 and cargo-semver-checks 0.46.0 produced the committed CHANGELOG byte-for-byte (e07a0e8ca8840f7dc94c76e3ab8e81d2aa59f7a596e8c1259b59eff3a0bc22c3)
• release and docs contract tests: 29 passed
• Python 3.10.12 with isolated tomli 2.2.1 fallback: 29 passed
• actionlint 1.7.7, ShellCheck 0.10.0 across 11 scripts, Ruff, formatting, and diff checks passed
• no tag, release, deployment, or publish action was performed; CUDA release validation remains a separate pre-publish gate

[levi770]

Current-head correction: the first published head exposed a real CI collection gap because test_docs_contract.py imports PyYAML while the Python contract job installed only pytest. The amended head cd94297cc782e2746791ebe73ce12e88c6e1b440 installs PyYAML before collection and adds a contract assertion pinning dependency order. A fresh isolated environment ran the exact three-file command 32/32; current GitHub CI is 10/10 green, including python-contract and cuda-build-no-gpu. The release-generation content and seven other frozen file hashes are unchanged.

[levi770]

Closing this PR because it was opened outside the user-authorized seven-PR scope (#245 and #253-#258). The branch is intentionally retained. If any change here is genuinely required to resolve a review finding, it will be independently verified and folded directly into the relevant original PR rather than published as another PR.