ci: publish canjv to Homebrew after PyPI releases

[rahlk]

Java's PyPI wheel already installs canjv with a JVM supplied by jdk4py, but releases do not publish a Homebrew formula. Add a job after successful PyPI publication that generates a pinned uvx formula from the published wheel's URL and SHA256 and updates the shared tap, following codeanalyzer-python's approach.

The formula exposes canjv; its first invocation downloads the pinned package and JVM. The workflow retries PyPI metadata retrieval, treats unchanged formulas as a no-op, and keeps tap failures separate from publication. The README documents the Homebrew command and first-use behavior.

Closes #225.

Validation:

• actionlint .github/workflows/release-pypi.yml, bash -n packaging/homebrew/generate_formula.sh, and git diff --check pass.
• Generated the formula from the published 3.0.2 wheel and independently verified the downloaded wheel's SHA256 against PyPI metadata.
• Loaded the formula with Homebrew's Ruby API, installed the launcher in a temporary directory, and verified its dependency, version pin, executable permissions, shell syntax, and argument forwarding.
• Invoked the generated launcher against the real PyPI package: canjv --version prints 3.0.2.
• Generator rejects malformed versions and checksums.

Release plan: ship this automation with the next release. Backfill the shared tap with the existing 3.0.2 wheel now; no new analyzer release or SDK pin bump is required. This PR does not change analyzer code or the schema.

Deployment prerequisite: ensure HOMEBREW_TAP_TOKEN is available to this repository with write access to codellm-devkit/homebrew-tap. No repository-level secret was listed; an organization secret may already provide it. The cross-repository CI push has not been exercised locally.

Propagation verdict: homebrew-tap (backfill the published 3.0.2 wheel). Sibling analyzers retain their existing packaging; SDK pins and analysis fixtures are unaffected. The analyzer README is updated; both docs-site installation guides were checked and have no existing Java Homebrew instructions to correct.