fix: replace Math.max/min spreads with iterative helpers to avoid stack overflow

[Mythie]

Math.max(...iterable) and Math.min(...iterable) spread into function
arguments, which overflows the call stack on large collections (~200k+).
PDFs with many xref/object-stream entries hit this during PDF.load().

Adds min/max helpers in src/helpers/math.ts that iterate without
spreading, and uses them in all affected call sites.

Closes #48

[vercel]

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Benchmark Results

Comparison

Load PDF

Benchmark	Mean	p99	RME	Samples
libpdf	2.29ms	3.20ms	±1.3%	219
pdf-lib	41.69ms	46.86ms	±4.5%	12

Create blank PDF

Benchmark	Mean	p99	RME	Samples
libpdf	61μs	119μs	±1.7%	8215
pdf-lib	456μs	1.77ms	±3.0%	1096

Add 10 pages

Benchmark	Mean	p99	RME	Samples
libpdf	106μs	182μs	±1.2%	4704
pdf-lib	537μs	1.99ms	±2.9%	932

Draw 50 rectangles

Benchmark	Mean	p99	RME	Samples
libpdf	335μs	810μs	±1.7%	1494
pdf-lib	1.62ms	5.69ms	±6.1%	308

Load and save PDF

Benchmark	Mean	p99	RME	Samples
libpdf	2.33ms	4.09ms	±1.9%	215
pdf-lib	86.98ms	95.69ms	±4.5%	10

Load, modify, and save PDF

Benchmark	Mean	p99	RME	Samples
libpdf	39.45ms	42.53ms	±2.0%	13
pdf-lib	85.92ms	90.67ms	±2.4%	10

Extract single page from 100-page PDF

Benchmark	Mean	p99	RME	Samples
libpdf	3.58ms	6.55ms	±2.0%	140
pdf-lib	9.15ms	10.59ms	±1.6%	55

Split 100-page PDF into single-page PDFs

Benchmark	Mean	p99	RME	Samples
libpdf	32.95ms	34.92ms	±1.5%	16
pdf-lib	92.17ms	107.13ms	±12.9%	6

Split 2000-page PDF into single-page PDFs (0.9MB)

Benchmark	Mean	p99	RME	Samples
libpdf	615.63ms	615.63ms	±0.0%	1
pdf-lib	1.68s	1.68s	±0.0%	1

Copy 10 pages between documents

Benchmark	Mean	p99	RME	Samples
libpdf	4.43ms	5.09ms	±1.0%	113
pdf-lib	11.89ms	13.11ms	±1.4%	43

Merge 2 x 100-page PDFs

Benchmark	Mean	p99	RME	Samples
libpdf	14.20ms	20.56ms	±3.0%	36
pdf-lib	53.76ms	54.88ms	±0.7%	10

Copying

Copy pages between documents

Benchmark	Mean	p99	RME	Samples
copy 1 page	1.01ms	2.54ms	±2.8%	497
copy 10 pages from 100-page PDF	4.42ms	5.00ms	±0.8%	114
copy all 100 pages	7.15ms	7.75ms	±0.9%	70

Duplicate pages within same document

Benchmark	Mean	p99	RME	Samples
duplicate page 0	930μs	1.56ms	±1.5%	538
duplicate all pages (double the document)	875μs	1.35ms	±0.9%	572

Merge PDFs

Benchmark	Mean	p99	RME	Samples
merge 2 small PDFs	1.44ms	2.11ms	±1.1%	348
merge 10 small PDFs	7.27ms	9.30ms	±1.1%	69
merge 2 x 100-page PDFs	13.36ms	13.95ms	±0.7%	38

Drawing

benchmarks/drawing.bench.ts

Benchmark	Mean	p99	RME	Samples
draw 100 rectangles	563μs	1.45ms	±2.5%	889
draw 100 circles	1.29ms	2.92ms	±2.9%	389
draw 100 lines	489μs	1.20ms	±1.5%	1023
draw 100 text lines (standard font)	1.57ms	2.39ms	±1.6%	320
create 10 pages with mixed content	1.36ms	2.66ms	±2.3%	369

Forms

benchmarks/forms.bench.ts

Benchmark	Mean	p99	RME	Samples
get form fields	3.34ms	6.93ms	±4.1%	150
fill text fields	11.65ms	15.60ms	±4.3%	43
read field values	2.98ms	5.34ms	±2.0%	168
flatten form	8.51ms	12.54ms	±3.5%	59

Loading

benchmarks/loading.bench.ts

Benchmark	Mean	p99	RME	Samples
load small PDF (888B)	60μs	150μs	±0.8%	8308
load medium PDF (19KB)	91μs	178μs	±0.6%	5517
load form PDF (116KB)	1.34ms	2.40ms	±1.5%	374
load heavy PDF (9.9MB)	2.19ms	3.01ms	±1.1%	228

Saving

benchmarks/saving.bench.ts

Benchmark	Mean	p99	RME	Samples
save unmodified (19KB)	103μs	233μs	±0.9%	4839
save with modifications (19KB)	722μs	1.37ms	±1.3%	693
incremental save (19KB)	160μs	343μs	±1.0%	3125
save heavy PDF (9.9MB)	2.22ms	2.68ms	±0.6%	226
incremental save heavy PDF (9.9MB)	4.79ms	11.59ms	±5.6%	105

Splitting

Extract single page

Benchmark	Mean	p99	RME	Samples
extractPages (1 page from small PDF)	990μs	1.92ms	±2.3%	506
extractPages (1 page from 100-page PDF)	3.57ms	6.11ms	±1.9%	141
extractPages (1 page from 2000-page PDF)	56.67ms	57.80ms	±0.9%	10

Split into single-page PDFs

Benchmark	Mean	p99	RME	Samples
split 100-page PDF (0.1MB)	30.76ms	34.99ms	±2.6%	17
split 2000-page PDF (0.9MB)	596.52ms	596.52ms	±0.0%	1

Batch page extraction

Benchmark	Mean	p99	RME	Samples
extract first 10 pages from 2000-page PDF	58.02ms	60.00ms	±1.2%	9
extract first 100 pages from 2000-page PDF	60.64ms	62.37ms	±1.4%	9
extract every 10th page from 2000-page PDF (200 pages)	64.77ms	66.18ms	±1.6%	8

Environment

• Runner: Linux (X64)
• Runtime: Bun 1.3.10

Results are machine-dependent.