Compiles deployment prelude SOURCE into a %PtcRunner.Lisp.Prelude{} artifact (Capability Prelude V1, plan §1 / §3).

What this does

1. Parses the prelude source to raw AST.
2. Walks the top-level program treating (ns name "doc" {meta}) as a COMPILER-ONLY directive (not a general user-runtime form), and defn/defn- as export/private-helper definitions under the current namespace.
3. Runs compile-time validation that does NOT depend on a selected runtime: reserved-namespace rejection, missing/invalid namespace, duplicate public refs, invalid visibility, invalid arity/signature metadata. Failures are returned as {:error, %PtcRunner.Lisp.Prelude.ValidationError{}}.
4. Builds %Export{} records for public definitions, normalizing kebab-case PTC-Lisp metadata keywords (:provider-ref) at the host boundary and inferring backing metadata only for literal (tool/call {:server "x" :tool "y" ...}) patterns (plan §3).
5. Captures a callable private prelude env by analyzing+evaluating the definition forms (ns directives stripped, defn- rewritten to defn) through the existing PTC-Lisp pipeline. The captured value is the resulting user_ns map (bare symbol => {:closure, ...}). NOTE: the evaluator's lexical closure capture does NOT fold sibling top-level defs into each closure's captured_env — sibling helpers resolve by name through user_ns at CALL time. The whole private_env map IS that namespace, so P2 must thread private_env as the user_ns layer when invoking an export for siblings to resolve (fact #6 capture seam, proven end-to-end during P0).
6. Computes a sha256 source hash (plan §12).

Attach-time requires validation against a selected upstream runtime is a SEPARATE later phase and is not performed here.