Fix pipeline: full seed assembly, array indexing, args() API

- compiler.el: rename 'seed' var to 'seed_json' (El compiler emits
  EL_NULL for bare 'seed' identifier — naming collision in codegen)
- compiler.el: build_seed() now assembles all five sections
  (values, biography, reasoning_patterns, relationships, voice_profile)
  instead of only values
- install.el: switch array indexing from json_get_raw(arr, "0") to
  json_get(seed_json, "values.0") dot-path notation — json_get_raw
  uses flat object key lookup and cannot traverse JSON arrays;
  json_get() uses json_path_descend() which handles numeric indices
- probe.el, forge.el: fix args() indexing (args() skips argv[0];
  index 0 is first real arg, not program name)

Forge pipeline now fully operational end-to-end.

src/probe.el

@@ -55,8 +55,8 @@ fn probe_main() -> String {
     // Determine subject name
     let argv: [String] = args()
     let subject: String = ""
-    if len(argv) > 2 {
-        let subject = get(argv, 2)
+    if len(argv) > 1 {
+        let subject = get(argv, 1)
     }
     if str_eq(subject, "") {
         println("[forge] usage: forge probe <name>")