The loop variable `n` in `toStringAs` was assigned without `local`,
leaking a global and tripping luacheck ("setting non-standard global
variable n"). Adding `local` confines it to function scope and clears
the cascade of related warnings. No behaviour change.

Closes purescript-lua#1

fix: declare `n` local in Data.Int.toStringAs

…pts/build, run test via bash)

chore: normalize build tooling (purescript-overlay, nix CI, Lua 5.1)

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.

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

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.

PureScript Int is 32-bit two's complement; the Lua FFI diverged from the
JS semantics the package's own test suite encodes:

- fromNumber returned Just for any Number (truncating the fraction); now
  Just only for an integral value inside the Int32 range, else Nothing.
- fromStringAs accepted fractional and out-of-range strings and, for
  non-decimal bases, Lua's `tonumber` turned a leading '-' into a huge
  unsigned value. It now parses the sign itself, validates every digit
  against the base (rejecting floats/whitespace/illegal chars) and range-
  checks the result, so e.g. `fromStringAs hexadecimal "-ef" == Just (-239)`.
- toStringAs emitted uppercase digits; JS toString(radix) is lowercase
  (`toStringAs hexadecimal 255 == "ff"`).
- rem used Lua's floored `%` (sign of the divisor); now the truncated
  remainder with the sign of the dividend, consistent with `quot`.
- pow returned a float and never wrapped; now `Math.pow(x,y) | 0`
  (truncate toward zero, wrap to Int32), so `pow 2 (-1) == 0`.
- and/or/xor only looped while operands were positive, giving wrong
  results for negatives; they now operate on the unsigned 32-bit
  representation over a fixed 32 bits (`and (-1) 5 == 5`, `xor (-1) 0 == -1`).
- shl/shr/zshr used `math.pow`/division with no masking or wrapping; they
  now implement JS 32-bit shifts (count mod 32; shl/shr re-signed, zshr
  zero-fill), so `shl 1 31 == -2147483648` and `zshr (-8) 1 == 2147483644`.

Shared 32-bit helpers live in each file's foreign header. Adds a Lua 5.1
regression guard (test/regression/int.lua) and a scripts/test runner.

Fixes purescript-lua/purescript-lua#85
Fixes purescript-lua/purescript-lua#86
Fixes purescript-lua/purescript-lua#87
Fixes purescript-lua/purescript-lua#88
Fixes purescript-lua/purescript-lua#89
Fixes purescript-lua/purescript-lua#90
Fixes purescript-lua/purescript-lua#91