[Kinflou]

The CLI half of ComlineProject/generation#101 (generation#102).

• Every version by default. Every release and dev build in the CAS chain, then the unreleased working state when its frozen schemas or headers differ from the last build. Each version's model carries the changelog from the version before it in the list, computed with comline_core::doc::changelog, which uses the same rules as comline diff.
• Paths. Output goes to <out>/<format>/<version>/, with unreleased/ for the working tree. Then the renderer's site index goes at <out>/<format>/: index.html, versions.js and compare.html for HTML, and index.md for Markdown. json writes <version>/model.json plus index.json.
• Caching. <out>/<format>/.comline-doc.json keys each version folder by its commit, the previous version's commit, the renderer id and version (plus the CLI version for built-ins, or the file's blake3 hash for [doc] renderer), the model version and links. A folder whose key matches is kept. The unreleased state always re-renders, and folders of versions no longer listed are removed.
• [doc] versions ("all", { last = N }, { since = "v" }, { releases_only = true }, which combine). --version renders one version alone into its folder, and --changelog-from applies only there; without --version it warns.
• --format is repeatable or comma-separated, and [doc] format becomes formats.
• Notes for old versions. A version without a docs tree entry (from before core#152) says it has no headers. A version whose protocols have no wire summary (core#153) says so.
• comline new's .gitignore adds docs/api/html/.
• docs/cli.md is updated.

Tests: the existing doc tests are moved to the new paths. New tests:

• every_version_is_documented_and_a_second_run_rerenders_only_unreleased: a marker survives in a kept folder and is wiped in unreleased/, and the second run reports "1 rendered, 5 unchanged".
• doc_versions_trims_the_list.
• html_writes_a_self_contained_site_per_version.

The external-renderer equivalence tests drop the manifests, which name their renderer, before comparing.

Pins: comline-codegen, comline-doc-markdown and comline-doc-html at generation 6889d3d; comline-rust 0e39319 (comline-rust#90); comline-typescript ad87568 (comline-typescript#109). Core is unchanged at 5259393.

Generated code is byte-identical. I ran comline generate with main's binary and with this branch's on simple_project, chat_project and validated_project. Each project declared Rust and TypeScript, and I also ran --target rust --mode lib. diff -r found no differences.

Cache key and renderer changes. A built-in renderer's key uses its content-hashed version (generation 6889d3d), so a CLI with a changed renderer re-renders every folder. cache_key() and Manifest::reuses() are unit-tested in a_changed_renderer_invalidates_every_folder.