scale schematic font sizes to em-height and render image borders

[anil08607]

Summary

Fixes schematic text sizing overflow and missing image borders in rendered SVGs (specifically observed on sheet 57 of ti-tmds62levm-rev-b around the "SCREW & WASHER FOR PCIe M.2" section):

1. Schematic Font Size Scaling:

   • In Altium Designer schematic documents, the SIZE parameter defines font cell height / line spacing in 10-mil units ($1.25 \times \text{em-height}$). Direct assignment to SVG font-size resulted in text rendering ~25% larger than in Altium Designer, causing headers such as "SCREW & WASHER FOR PCIe M.2" (SIZE=25) to overflow their bounding boxes.
   • Introduced SCHEMATIC_FONT_SIZE_SCALE = 0.8 in lib/svg-serialization/get-schematic-font.ts to convert Altium cell height into standard SVG typographical em-square font size.
   • Headers, parameter values, and designators now fit cleanly within their intended margins.

2. Schematic Image Border Rectangle:

   • Altium image records (RECORD=30) specify a border color via the Color field (e.g. Color=128 / #800000 on the washer drawing in Sheet 57).
   • Added border rectangle rendering (<rect data-record="30" ... fill="none" stroke="${color}" stroke-width="${formatSvgNumber(lineWidth)}"/>) in lib/svg-serialization/serialize-altium-sheet-to-svg.ts when COLOR is defined on the record.

3. Snapshots & Test Coverage:

   • Updated tests/svg/ti-tmds62levm-schematic-sheets.test.ts to include Sheet 57 in snapshot assertions.
   • Updated tests/svg/__snapshots__/ti-tmds62levm-schematic-sheets-sheet-57.snap.svg and existing affected SVG snapshots.
   • Added tests/svg/schematic-sheet-57-screw-washer.test.ts to guard against regressions for text bounding and washer borders.

Verification

• bun test: All 228 tests passing across 96 suites (including 57/57 TI TMDS62LEVM schematic sheets).
• bun run typecheck: Passed with 0 errors.
• bun run format:check: Passed.
• bun run build: Clean build.

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[ShiboSoftwareDev]

Font size scales based on the font, and different fonts can be used