Replace the inherited bower CI (no bower.json in this fork) with a nix-based one that runs scripts/build, scripts/test (if present) and luacheck; make the scripts fail-fast; refresh stale flake inputs.

chore: normalize build tooling (nix CI, fail-fast scripts, fresh flake)

CI: drop accept-flake-config (supply-chain risk; caches already pinned),
run luacheck with --std lua51 --no-unused-args (matches the Lua 5.1 target
and the curried-FFI idiom), invoke the test step via bash so it no longer
needs the execute bit.

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 JavaScript-era package files. Tooling and docs only, no src/.

chore: align CI to the hardened canon, add AGENTS.md

Repos moved from Unisay/* to the purescript-lua org. Update the pslua
flake input and lockfile owner (same rev 94c13ce), the packages.dhall
upstream-lua release URL, and the AGENTS.md links, so nothing relies on
the old-owner redirect.

chore: point pslua + package-set links at purescript-lua org

Wire treefmt via treefmt-nix: nixfmt, dhall format, purs-tidy (.tidyrc.json)
and LuaFormatter for the FFI (.lua-format, kept over StyLua because it
preserves the parentheses pslua's parser needs). `nix fmt` formats; the dev
shell installs a content-based pre-commit hook and CI runs
`nix fmt && git diff --exit-code` (content-based, since the in-place
formatters bump mtime and would trip treefmt --fail-on-change). Lua lines
budget 130 cols, matching the raised `luacheck --max-line-length`. The bulk
of the diff is the first format pass.

chore: add treefmt formatting (nix fmt + pre-commit + CI check)

Replace the dev-shell installer that wrote .git/hooks/pre-commit with a
tracked .githooks/pre-commit wired via `git config core.hooksPath .githooks`.

Fixes three issues with the old hook: it gated on `[ -d .git ]` (false in
worktrees/submodules where .git is a file), it clobbered any existing
.git/hooks/pre-commit on every `nix develop`, and `nix fmt … || exit 0`
swallowed real formatter failures. The new hook skips only when `nix` is
absent (CI is the authoritative gate) and otherwise blocks on a `nix fmt`
failure or reformat.

Toolchain consistency: pin the pslua dev flake input to the current
compiler main across the ecosystem. flake.lock only; the package set
consumes sources + FFI, not this dev input, so no re-tag is needed.

pslua compiles a PureScript Char as a Lua string of its UTF-8 bytes, so
the Char FFI must use code points across the whole 0..65535 range:

- toCharCode decoded only the first byte (`c:byte()`), so 'é' (U+00E9)
  gave 195 instead of 233 and `cardinality`/`fromEnum` were wrong above
  U+007F. It now decodes the first UTF-8 code point (JS c.charCodeAt(0)).
- fromCharCode was bound to `string.char`, which errors above 255 and
  emits a lone raw byte for 128..255. It now UTF-8-encodes the code point
  (JS String.fromCharCode), so charToEnum/toEnum/succ/pred work for any
  Char instead of throwing above U+00FF.

Adds a Lua 5.1 regression guard (test/regression/enum.lua) and a
scripts/test runner.

Fixes purescript-lua/purescript-lua#79
Fixes purescript-lua/purescript-lua#80

The v6.1.1 rewrite assumed every Char is a complete UTF-8 sequence and
read c:byte(2..4) unconditionally. But Data.String.CodeUnits slices a
String byte-wise (toCharArray = s:sub(i,i)) and Data.String.CodePoints
reassembles code points itself, so toCharCode is routinely called on a
single lead/continuation byte — where c:byte(2) is nil and the arithmetic
crashes (caught by the StringCodePoints eval golden on CI).

Length-guard the decode: assemble the full code point only when the whole
sequence is present (#c >= expected), else return the lead byte (the
byte-in/byte-out behavior the CodePoints layer relies on). The Char-literal
decoding from #79 is preserved. Adds lone-byte regression cases.

Fixes purescript-lua/purescript-lua#102