Add examples and package CI

[lukewilliamboswell]

Scope:

• Add a broad examples/ suite for the current package API using the Zig platform template.
• Add package bundling via scripts/bundle.sh.
• Add CI coverage for formatting, package check/test/docs, bundling, and examples tested against a localhost-served package URL.
• Add a manual release workflow that builds a package bundle, tests the exact bundle artifact, and publishes it to a GitHub release.

Intentional non-goals:

• This PR is not trying to settle API or package design questions.
• Follow-up PRs can revisit Request/Response opacity, module layout, naming, and broader design/API changes.

Validation run locally:

• ci/all_tests.sh
• scripts/bundle.sh --output-dir /private/tmp/roc-http-release-bundle
• python3 ci/test_bundle_examples.py --bundle-path /private/tmp/roc-http-release-bundle/6LcdNq2r7xTBwj972ecYWUkMWobJr94yL2NyJpHRAXap.tar.zst