Fix indentAllLines applying the indent more than once

[MahathirMohammadShuvo]

What kind of change does this PR introduce?

Bug fix. Fixes #1606.

indentAllLines keeps the indent in effect after the first line, but nothing tracked whether it had already been applied. nextSection() re-applied it on every page break, and the firstLine handler re-applied it on every paragraph, so the indent accumulated instead of staying put.

With width: 300, indent: 15, indentAllLines: true:

	before	after
x on each paragraph of a multi-paragraph wrap	15, 30, 45 …	15 on every paragraph
lineWidth after successive page breaks	285 → 270 → 255 …	285 on every page
page break before the first line (orphan check)	indent applied twice	applied once

lineWidth carries over between pages while addPage() resets document.x, so subtracting the indent again on every page break narrowed the text column further and further. With enough pages it reaches zero, no word fits on a line, and pagination runs away — that reproduces as an out-of-memory crash.

This is a regression from the fix for #1686, which added the indent restore in nextSection() without accounting for the firstLine handler having already applied it.

Continued text (#1606)

Continued segments inherit the previous call's options, so a follow-on text() is also indentAllLines and took the same early return — which meant the continuation offset was never taken back off and every line of the continued segment sat at the offset where the previous segment happened to end:

doc.text(long, { width: 300, indent: 15, indentAllLines: true, continued: true });
doc.text(long, { width: 300 });

line	before	after
first line of the continued segment	x = 195.1	x = 195.1 (carries on from the previous segment)
every line after it	x = 195.1, lineWidth 104.9	x = 15, lineWidth 285

The continuation offset belongs to the first line of a segment only, so it is now taken back off after that line while the paragraph indent stays on.

Checklist:

• Unit Tests
• Documentation — N/A, no API or option change
• Update CHANGELOG.md
• Ready to be merged

Four regression tests added to tests/unit/line_wrapper.spec.js, covering paragraphs, page breaks, the orphan check path where the page break runs before firstLine, and continued text. All four fail against the current lib/ and pass with the fix. Full unit suite passes, 384/384.

[MahathirMohammadShuvo]

Updated the branch. While checking this against continued text I found the same root cause behind #1606, so the scope grew slightly: continued segments inherit the previous call's options, so the follow-on text() is also indentAllLines and took the same early return, leaving the continuation offset applied to every line of the segment instead of just the first.

The description above has the before/after numbers. Fourth regression test added for it; the suite is green at 384/384.

[blikblum]

Please fix the conflict