Migrate to Bun 1.4 and MIT

[sadfun]

Summary

• pin Bun 1.4.0 across package metadata, CI, release builds, and Docker
• migrate bun.lock to the Bun 1.4 v2 lockfile format
• replace marked and the external Codex tar subprocess with Bun.markdown and Bun.Archive
• replace FSL-1.1-MIT with the MIT License and update project documentation

Verification

• Bun 1.4.0 frozen install
• bun run check
• bun test (6 passing)
• bun run compile and compiled binary smoke test
• real pinned Codex package extraction with executable permission verification
• Docker image build and container smoke test

[greptile-apps]

Greptile Summary

The PR consistently migrates development, CI, release, and container builds to Bun 1.4.0 while adopting the MIT License.

• Pins Bun 1.4.0 in package metadata, GitHub Actions, and the Docker build stage.
• Updates the lockfile marker to Bun's v2 format.
• Replaces FSL licensing text and references with MIT.

Confidence Score: 5/5

The PR appears safe to merge with no concrete blocking or non-blocking defects identified.

The changed runtime declarations are consistent across supported build targets, the reported frozen install covers the migrated lockfile, and repository-facing licensing references consistently identify MIT.

Important Files Changed

Filename	Overview
package.json	Adds the Bun package-manager pin, raises the minimum Bun version, and changes package licensing metadata to MIT.
bun.lock	Updates the lockfile format marker from version 1 to version 2 without changing dependency resolutions.
Dockerfile	Pins the build-stage image to Bun 1.4.0 while leaving runtime image construction unchanged.
.github/workflows/ci.yml	Makes CI installation, checks, compilation, and smoke testing run with Bun 1.4.0.
.github/workflows/release.yml	Pins release verification and installation steps to Bun 1.4.0.
LICENSE.md	Replaces the former FSL terms with standard MIT License text.
README.md	Raises the documented Bun requirement and updates the project license description.
CHANGELOG.md	Records the Bun 1.4 toolchain migration and MIT relicensing.

_{Reviews (1): Last reviewed commit: "Migrate to Bun 1.4 and MIT" | Re-trigger Greptile}