docs: point the install one-liner at v0.4.2 #381

docs: point the install one-liner at v0.4.2

Component: the edited files are existing files at the repository root, in docs/ and in scripts/. No new files.

v0.4.2 is published (https://github.com/DanielNetzer/forgecell/releases/tag/v0.4.2), built from main 63961ea. Its anonymous install is verified. This follow-up is the same as #375/#378 for v0.4.1.

Change (text only): every reference that names the current pinned release moves from v0.4.1 to v0.4.2:

• README.md:
  • line 31, the downloadable release;
  • the installer <summary> line;
  • the one-liner URL (.../download/v0.4.2/install.sh);
  • "pins the published public-core v0.4.2 release";
  • "The v0.4.2 release defaults to…".
• docs/install.md:
  • line 3 ("Public CLI v0.4.2 release");
  • the one-liner URL;
  • the Lab-directory sentence;
  • "The command above pins v0.4.2.";
  • "The pinned installer uses … the v0.4.2 tag."
• scripts/test-native-installer.py: public_url points at v0.4.2.

Keep unchanged the release-history sentences, which stay true. TestMoleculeFindingsDocs pins some of them:

• every "v0.4.0 …" sentence (plugins first shipped in v0.4.0);
• the "v0.4.1 hardens them: …" sentence in the versions paragraph;
• lab/plugins/README.md.

In the versions paragraph, append after the "v0.4.1 hardens them…" sentence: "v0.4.2 makes loop --watch print only what changed after its first pass, and tells a later coding attempt which files an earlier attempt already changed."

Scope: README.md, docs/install.md, scripts/test-native-installer.py.

Done when

• No reference in these three files names v0.4.1 as the pinned or downloadable release, and the release-history sentences above are byte-identical.
• The Formula baseline checks pass, with no protected delta.

Plan checks for this slice

Use only the Formula baseline checks; no candidate Go test is needed because no Go code changes. Every plan check leaves reviewedAcceptance and independentProvenance empty.