feat(WOR-TSK-194): implement bumpSnapshot NAPI function

[miguelramos]

• Add bumpSnapshot function for generating temporary snapshot versions
• Support format template with variables: {version}, {branch}, {short_commit}, {commit}, {timestamp}
• Validate snapshot format contains at least one valid variable
• Snapshots do NOT consume/archive changesets (no_archive=true, no_changelog=true)
• Return packages with originalVersion and snapshotVersion

Implementation details:

• convert_to_napi_snapshot: Convert CLI response to NAPI types
• parse_snapshot_response: Parse JSON from CLI to BumpSnapshotData
• validate_snapshot_params: Validate root path and snapshot format
• convert_snapshot_params_to_args: Convert NAPI params to CLI args
• DEFAULT_SNAPSHOT_FORMAT constant: {version}-snapshot.{short_commit}

Tests:

• Add 50 comprehensive tests for bumpSnapshot
• shared_buffer_tests (6 tests)
• parse_response_tests (10 tests)
• conversion_tests (8 tests)
• validation_tests (17 tests)
• bump_types_tests (9 existing tests)

Node.js bindings:

• Regenerate bindings with build-binding:release
• Update index.ts exports with bumpSnapshot function
• Update TypeScript type definitions

Story 5.4 complete - all 746 tests passing, 0 clippy warnings