scaffold-project.py and family.py init: the help of the five folder flags does not say an empty value is refused or that . is this directory, and validate-manifest.py's docstring says a leg with a bad repository: is left out #999

Goal: each folder flag's --help says what #972 makes true of an empty value and of ., and _run_products's docstring names only the legs the naming gate leaves out.

Filed by lane openRepoShape-3, from RV972's round-2 review of #972, its N6 (comment 6269253127), and RV981's round-2 review of #981, its NIT 1 (comment 6266667805).

State. Read at origin/main c7a3ff16. #981 is merged. #972 (closes #911 and #930) is READY and not yet merged, and the first part applies once it lands.

What happens.

1. scaffold-project.py and family.py init: a flag passed empty is refused by name, a passed --id is told what an id may hold once the name passes, and an empty folder this user cannot list is told the permission (#911, #930) #972 refuses five folder flags passed empty: the scaffold's --work-dir and --local-remote-dir, and family.py init's --into, --work-dir and --local-remote-dir. The codes are work-dir-no-path, local-remote-dir-no-path and into-no-path, and a typed . still means this directory. No --help says so (scaffold-project.py:370-372 and :423-425, and scripts/family.py:9663-9678 at main). --pin-source is the precedent: its pin-source-no-path is written down only in its --help, and from there in docs/cli.md (:390 and :555).
2. _run_products's docstring (templates/assembly-root/scripts/validate-manifest.py:226-230) says the naming gate's _project_chain_links leaves out "a leg whose repository: is bad or missing". It leaves out only a missing one: scripts/validate-repository-naming.py asks "repository" not in leg (about :934-936). The run fails either way, so only the words are wrong.

Evidence.

• RV972 ruled that the new codes need no doc before scaffold-project.py and family.py init: a flag passed empty is refused by name, a passed --id is told what an id may hold once the name passes, and an empty folder this user cannot list is told the permission (#911, #930) #972 lands. tests/test_agents_md_codes.py only checks that a code AGENTS.md names is printed, and tests/test_cli_reference.py holds docs/cli.md to --help. Matching pin-source-no-path means one clause in each flag's help.
• RV981 measured that the gate keeps a leg whose repository: is present and bad, and leaves out a leg with none.

Direction.

• Add one clause to each of the five flags' help=, for example "an empty value is refused as <flag>-no-path, and . means the directory the run stands in". Then regenerate docs/cli.md with scripts/render-cli-reference.py. AGENTS.md and the handbook need nothing.
• In _run_products's docstring, write "missing" for "bad or missing". This file is the assembly root's pinned copy, so even a one-word change re-pins every project. Take it with the next change to that file, not on its own.

Verify.

• tests/test_cli_reference.py passes with the regenerated docs/cli.md, and each tool's --help shows the clause.
• tests/test_repo_hygiene.py and the pinned-copy tests pass with the docstring word changed.

Size. Small: five help strings, one regenerated doc, and one docstring word.

Lane: openreposhape-3 (openRepoShape-3)