Release base-bash-libs v1.4.0

[codeforester]

Scope

Prepare and publish base-bash-libs v1.4.0 after completing the logging
hardening and compatibility train in #194, #195, and #196.

Release checklist

• Merge Stop implicit argv logging #194, Harden the primary log sink #195, and Run logging smoke tests on Bash 4.2 #196 in order with fresh checks after each restack.
• Update VERSION, the README version row/example, and CHANGELOG.md.
• Run ./tests/validate.sh and git diff --check.
• Open and merge the release-preparation pull request.
• On synchronized, clean main, run basectl release check, plan,
  notes, and publish --dry-run for v1.4.0.
• Publish the guarded v1.4.0 GitHub Release.
• Verify the annotated tag and GitHub Release.
• Update and validate the Homebrew formula and bottles.
• Update Base's full-SHA dependency pins and validate Base.
• Record release and downstream links and clean up release branches.

Completion links

• Release preparation: Prepare base-bash-libs v1.4.0 release #198
• Release: https://github.com/basefoundry/base-bash-libs/releases/tag/v1.4.0
• Homebrew formula and bottles: Update base-bash-libs formula to v1.4.0 homebrew-base#83
• Base CI pin: Pin CI to base-bash-libs v1.4.0 base#1753

The release contract is declared in base_manifest.yaml; the detailed sequence
is documented in docs/release-process.md.

[codeforester]

Release train complete. v1.4.0 is published and verified; Homebrew PR #83 and Base PR #1753 are merged. The corrected ARM64 and Intel bottles passed their build and smoke jobs, and a consumer install poured base-bash-libs 1.4.0 plus Base 1.7.0 rebuild 4 from bottles; both formula tests passed.