fix(lint): detect timelines in local external scripts

[miguel-heygen]

What

• Load project-local <script src> files into the lint context.
• Use local external script contents for timeline registry and timeline ID checks.
• Add an end-to-end regression test for external timeline registration.

Why

Valid compositions that register window.__timelines in a local JavaScript file were incorrectly reported as missing_timeline_registry, forcing authors to duplicate the registration inline.

How

Project lint now resolves local script paths with the same project-root safety checks used for linked assets, ignores remote/data/blob scripts, and supplies the loaded source to timeline rules.

Test plan

• bun run --filter @hyperframes/cli test -- --run src/utils/lintProject.test.ts
• bun run --filter @hyperframes/lint test
• bun run --filter @hyperframes/lint typecheck
• bun run --filter @hyperframes/cli typecheck
• bunx oxlint packages/lint/src/types.ts packages/lint/src/context.ts packages/lint/src/project.ts packages/lint/src/rules/core.ts packages/cli/src/utils/lintProject.test.ts