Fix schematic text sizes in real Altium viewers

[techmannih]

Before

After

Summary

Real Altium viewers rendered exported schematic annotations much larger than intended when fractional font-table values such as SIZE=3.6 were interpreted inconsistently. Native pin records also need their dedicated custom-font fields.

This PR preserves the existing text sizes that were already correct, rounds generated font-table entries to whole points, and applies category-specific font IDs so the problematic text matches its intended reference text.

Text sizing relationships

• Component designator and MPN/value: 4 pt, matching the existing resistor designator/value size (R1, R2, etc.).
• Pin labels and pin numbers: 3 pt via NAME_CUSTOMFONTID and DESIGNATOR_CUSTOMFONTID.
• Trace inline labels: 3 pt, matching pin labels and pin numbers.
• Standalone/native net labels: 4 pt.

For example, the Rearview Mirror export now writes R21, 0Ω, U6, and TCAN1042HGVDRBQ1 at the same 4 pt size. Its CANH pin label, pin number, and inline trace label all use the same 3 pt font entry.

Regression coverage

• Verifies explicitly presented component designator/value text matches a fallback resistor designator/value.
• Verifies pin label/number sizing and dedicated custom font IDs.
• Verifies trace inline-label sizing matches the pin font.
• Verifies standalone net-label sizing.
• Ensures every generated SIZE* field is a whole-point value.
• Preserves imported Altium schematic round trips.
• Updates affected hierarchy rendering snapshots.

Verification

• bun test — 77 passed, 0 failed
• bun run typecheck — passed
• bun run format:check — passed
• git diff --check — passed
• Generated the TI SystemBlock UI Rearview Mirror example locally through the linked converter and inspected its native SchDoc records.

No generated Altium ZIP or other binary artifact is included in this PR.

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