refactor(lua): table-drive namespace install in lua/api/mod.rs

[Kohei-Wada]

Where

• `ttymap-tui/src/lua/api/mod.rs:156-264, 268-810`

What

Adding a new `ttymap.` requires updating the namespace list in 4 places (install body, module-doc, tests, `ttymap_table_is_installed_with_namespaces`). The file is ~810 lines, mostly tests + module doc.

Proposal

Drive namespace install from a single `(name, builder)` table. New namespace = one line. Optionally split tests into a sibling submodule to shrink `mod.rs`.