Fix exponential compilation blowup in pattern matching and boolean si…

[cristianoc]

…mplification

This PR fixes two sources of exponential compilation time:

1. Boolean expression simplification (js_exp_make.ml): The simplify_and_ function had O(3^n) recursive behavior when simplifying nested AND expressions. Added a depth limit (10) to prevent exponential blowup while preserving optimizations for normal cases.

   Fixes the issue reported in Fix infinite recursion in E.econd when optimizing nested conditionals #8039 and repro large variant timeout #8042 (large unboxed variants). Note: PR Fix infinite recursion in E.econd when optimizing nested conditionals #8039's diagnosis of "infinite recursion" was incorrect - the actual issue was exponential blowup, not infinite loops.

2. Exhaustiveness checking (parmatch.ml): The exhaust_gadt function had exponential complexity (~4^n) when checking exhaustiveness for dict pattern matching. Added a call count limit (1000) that conservatively reports non-exhaustive when exceeded, preventing hangs while maintaining correctness.

Performance improvements:

• Large unboxed variants (28 cases): 3.79s -> 0.03s (126x faster)
• Dict pattern matching (6 cases): 0.94s -> 0.04s (24x faster)

Added test cases for both scenarios.

Closes #8074
Closes #8039
Closes #8042

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commit: bb596f7

[cknitt]

🎉

[nojaf]

This lead to some unfortunate output when upgrading:

For

    k->Context.onKeyRelease(key => {
      switch key {
      | Space => fly(bird)
      | _ => ()
      }
    })

I now get:

  k.onKeyRelease(key => {
    if ((key === "f6" || key === " " || key === "f7" || key === "space" || key === "f8" || key === "meta" || key === "f9" || key === "alt" || key === "f10" || key === "control" || key === "f11" || key === "tab" || key === "f12" || key === "enter" || key === "`" || key === "backspace" || key === "1" || key === "escape" || key === "2" || key === "/" || key === "3" || key === "." || key === "4" || key === "," || key === "5" || key === "m" || key === "6" || key === "n" || key === "7" || key === "b" || key === "8" || key === "v" || key === "9" || key === "c" || key === "0" || key === "x" || key === "-" || key === "z" || key === "+" || key === "'" || key === "=" || key === ";" || key === "q" || key === "l" || key === "w" || key === "k" || key === "e" || key === "j" || key === "r" || key === "h" || key === "t" || key === "g" || key === "y" || key === "f" || key === "u" || key === "d" || key === "i" || key === "s" || key === "o" || key === "a" || key === "p" || key === "\\" || key === "[" || key === "]") && key === "space") {
      return fly(bird);
    }
  });

where I had:

   k.onKeyRelease(key => {
     if (key === "space") {
      return fly(bird);
    }
  });

and key is:

@unboxed
type key =
  | @as("f1") F1
  | @as("f2") F2
  | @as("f3") F3
  | @as("f4") F4
  | @as("f5") F5
  | @as("f6") F6
  | @as("f7") F7
  | @as("f8") F8
  | @as("f9") F9
  | @as("f10") F10
  | @as("f11") F11
  | @as("f12") F12
  | @as("`") Backtick
  | @as("1") One
  | @as("2") Two
  | @as("3") Three
  | @as("4") Four
  | @as("5") Five
  | @as("6") Six
  | @as("7") Seven
  | @as("8") Eight
  | @as("9") Nine
  | @as("0") Zero
  | @as("-") Minus
  | @as("+") Plus
  | @as("=") Equals
  | @as("q") Q
  | @as("w") W
  | @as("e") E
  | @as("r") R
  | @as("t") T
  | @as("y") Y
  | @as("u") U
  | @as("i") I
  | @as("o") O
  | @as("p") P
  | @as("[") LeftBracket
  | @as("]") RightBracket
  | @as("\\") BackwardSlash
  | @as("a") A
  | @as("s") S
  | @as("d") D
  | @as("f") F
  | @as("g") G
  | @as("h") H
  | @as("j") J
  | @as("k") K
  | @as("l") L
  | @as(";") Semicolon
  | @as("'") Quote
  | @as("z") Z
  | @as("x") X
  | @as("c") C
  | @as("v") V
  | @as("b") B
  | @as("n") N
  | @as("m") M
  | @as(",") Comma
  | @as(".") Period
  | @as("/") ForwardSlash
  | @as("escape") Escape
  | @as("backspace") Backspace
  | @as("enter") Enter
  | @as("tab") Tab
  | @as("control") Control
  | @as("alt") Alt
  | @as("meta") Meta
  | @as("space") Space
  | @as(" ") SingleSpace
  | @as("left") Left
  | @as("right") Right
  | @as("up") Up
  | @as("down") Down
  | @as("shift") Shift
  | @as("string") String(string)

[cristianoc]

My motivation for looking into this further has decreases as the bug reports from users have been fixed.

[nojaf]

Fair enough