Tracker: Legacy server bug fixes, 90% coverage gate #5075

Summary

Tracks the legacy-era work that ships in v1.0.0: characterization test suites with a per-file 90% coverage gate for every server, fixes for the known bugs those suites pinned, and the migration of every server to the v2 TypeScript and Python SDKs. No protocol-era change.

These sub-issues were split out of #4857 (Tracker: 2026-07-28 Spec Refactor), which keeps the modern-era work for v2.0.0.

Sub-issues

• Bugs, Coverage, and SDK Wave 1 Part 1: TypeScript servers: extensive unit tests + per-file 90% coverage gate #4854 TypeScript servers: extensive unit tests + per-file 90% coverage gate
• Bugs, Coverage, and SDK Wave 1 Part 2: Python servers: extensive unit tests + per-file 90% coverage gate #4855 Python servers: extensive unit tests + per-file 90% coverage gate
• Bugs, Coverage, and SDK Wave 2: fix the known bugs the Wave 1 suites pin (legacy-era servers) #5004 Fix the known bugs the test suites pin (legacy-era servers)