chore: add AGENTS.md + CLAUDE.md, drop dead JavaScript-era files

AGENTS.md is the single instruction file the coding agents read natively;
CLAUDE.md is a one-line @AGENTS.md import so Claude Code shares it. Also
removes dead bower.json/package.json/.eslintrc.json. CI is already on the
shared canon; no src/ change.

Author: Unisay

.eslintrc.json

@@ -0,0 +1,41 @@
+# AGENTS.md
+
+A PureScript→Lua FFI fork in the [`purescript-lua`](https://github.com/Unisay/purescript-lua) package set. Generated code targets **Lua 5.1**.
+
+## Commands
+
+All commands run inside the nix dev shell:
+
+- Build: `nix develop -c ./scripts/build`
+- Test: `nix develop -c bash ./scripts/test` (only forks that ship Lua regression tests have one)
+- Lint: `nix develop -c luacheck --quiet --std lua51 --no-unused-args src/`
+
+## Lua 5.1 target
+
+The output runs on Lua 5.1, which is stricter than 5.3:
+
+- No `table.unpack`, `bit32`, `utf8`, or the `//` operator. `math.pow` and `math.atan2` do exist.
+- Array-style tables are 1-indexed: the first element is `t[1]`, not `t[0]`.
+- `unit` is `{}`, never `nil`: a `nil` table element silently disappears, which would collapse `Array Unit` into an empty table.
+- Lua 5.1 mangles some Lua 5.3 string escapes, so keep FFI string escapes 5.1-safe.
+
+## FFI files (`src/*.lua`)
+
+pslua's foreign-file parser needs every exported value wrapped in parentheses:
+
+```lua
+return {
+  identity = (function(x) return x end),
+  answer = (42),
+}
+```
+
+A bare `function … end` or an unparenthesised expression fails to parse.
+
+## Toolchain
+
+`flake.nix` pins everything through [`purescript-overlay`](https://github.com/thomashoneyman/purescript-overlay): purs 0.15.16 (`purs-bin.purs-0_15_16`), spago 0.21.0 (`spago-bin.spago-0_21_0`), Lua 5.1 (`lua51Packages`). The `pslua` input tracks `github:Unisay/purescript-lua`; keep `flake.lock` reasonably current, since a long-stale pslua pin won't create the `--lua-output-file` directory and CI fails.
+
+## Releasing
+
+Tag-driven, with no GitHub Release or changelog entry. The full conventions live in the [package-set repo](https://github.com/Unisay/purescript-lua-package-sets/blob/master/CONTRIBUTING.md): push an annotated tag on `master`, bump this fork's `version` in the package set's `src/packages.dhall`, refresh `latest-compatible-sets.json`, and push a `psc-*` set tag.

AGENTS.md

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+@AGENTS.md