CI: no workflows exist yet

Tracking issue for CI. The repository currently has no workflows at all — nothing verifies that main compiles.

Each child is independent and one PR.

Children

• #34 — Build, typecheck and lint on PRs
• #33 — DCO sign-off
• #35 — Spell-check the course content
• #36 — Scheduled link check
• #37 — Manifest / content consistency check

Suggested order

#34 first, clearly. It type-checks the whole project, so it catches the widest class of breakage, and it is nearly free because the ESLint config and scripts already exist. Everything else is a refinement on top of knowing the thing builds.

#33 next — small, and it is org convention, so it may as well be in place before outside contributors arrive.

#35 and #36 are both content-quality checks, and both have the same failure mode: if they are noisy they get ignored, and an ignored check is worse than no check. The work in each is the tuning (a project dictionary; a flaky-link ignore list), not the wiring.

#37 grows in value as modules are written — with 17 files it is nice to have, with 87 it is essential.

Deliberately not doing yet

• Prettier / markdownlint — style bikeshedding on prose that is actively being written.
• REUSE compliance — the org expects license headers, and this should be added if the repo goes public (see #31, #30). Noise while private.

Treat this as a tracking issue rather than a standalone implementation; begin with child #34 and inspect the existing ESLint configuration and scripts. The tracking work is done when the independent child checks listed here have been completed, including a workflow that verifies the project builds.