Fix Windows release checks for line endings and native fonts

[dhsohn]

Motivation

I found that Windows release checks failed when Git checked out CRLF source files and when rendering tests compared design or offscreen font metrics with the native Windows font engine.

Changes

• Normalize source text only inside the JavaScript test harness and run the full behavioral suite from both LF and CRLF copies.
• Make the sdist rejection fixture independent of line endings while retaining its byte-change and rejection assertions.
• Reconstruct plain-label glyphs with device metrics; retain the previous 1/64-pixel tolerance with only a floating-point rounding allowance.
• Give the SVG oracle the product's Qt startup context, retain exact SVG and session-preservation assertions, and include its file in the serial native Windows gate.

Application code, package contents, version and public documentation are unchanged.

Verification

• Original JavaScript suite: LF 187 passed; CRLF 162 passed and 25 failed. Repaired harness: 187 passed with either line ending.
• Canonical selected Mac gate: 8,340 passed, 11 optional-RDKit skips; lint, formatting and type checks passed. Selected coverage: 50.65% lines and 38.22% branches.
• Full Mac gate: 16,979 passed, 428 skipped, 1,036 subtests passed; 94.39% line and 86.52% branch coverage. RDKit is absent locally and remains covered by its dedicated CI job.
• Wheel rebuilt from sdist, distribution inventory, metadata and five clean-installed CLI checks passed; neither artifact contains browser modules or assets.
• The release still requires successful exact-main Windows platform tests and separate actual canvas verification.