driver: implement post-target run argv semantics

docs/spec.md

@@ -703,6 +703,32 @@ ImportPath    = ident { "." ident } .
   arguments and result; this rule does not adopt Go's source signature. An
   ordinary import of a package declared `main` is rejected, except for the
   toolchain's colocated external-test wiring.
+- For `ww run`, the first explicit non-option operand selects the one run
+  target. Every later operand is program input and is passed unchanged and in
+  order after the private executable's `argv[0]`; it is not reparsed as a
+  driver option. This includes known or unknown option spellings, would-be
+  option values, a lone `--`, empty arguments, ordinary nonflags, and later
+  `.ww` spellings. A later `.ww` is therefore argv, not another source in a
+  command-line package; multiple named sources remain unsupported. Registered
+  driver options before the target retain their established spelling, value,
+  repetition, and diagnostic rules. A leading or otherwise pre-target `--`
+  retains WW's exact unknown-flag rejection rather than acting as a general
+  terminator. With no explicit target, `ww run` retains its implicit current-
+  directory selection and has no post-target suffix.
+  Only the selected target and pre-target driver options affect resolution,
+  source loading, package/import identity, graph construction, compiler,
+  assembler, archiver, linker, private executable bytes, reuse, or
+  invalidation. A missing, invalid, non-main, or producer-failing target
+  diagnoses before runtime and no suffix spelling can mask that result. A
+  successful private link executes with the exact suffix and retains WW's
+  existing stdout, stderr, and exact child-status propagation. The private run
+  product is removed normally and publishes no executable or persistent
+  semantic state. `ww build`, every `ww test` route, package membership, and
+  dotted import semantics are unchanged. Direct roots remain `__root.*`,
+  dotted directories retain dotted identity, and argv never becomes package,
+  import, action, symbol, artifact, `.wwi`, publication, or persistence
+  identity. Build workdir format remains 18, test workdir format remains 19,
+  and semantic storage format remains 3.
 - For `ww build`, the output-option name is exactly `o`. The accepted forms are
   `-o VALUE`, `--o VALUE`, `-o=VALUE`, and `--o=VALUE`. An equals form splits
   at its first `=` and preserves every later byte, including further `=`