fix: strip unsupported regex patterns from tool schemas

[ebbsanchez]

Summary

• remove provider-incompatible regex lookaround pattern fields from MCP tools/list JSON schemas
• keep the existing Zod runtime validators unchanged for actual tool calls
• add a regression test that walks every exposed tool schema and fails on lookaround patterns

Fixes #45.

Verification

• npm exec --yes pnpm@10 -- install --frozen-lockfile
• npm exec --yes pnpm@10 -- test src/server.test.ts
• npm exec --yes pnpm@10 -- format
• npm exec --yes pnpm@10 -- lint
• npm exec --yes pnpm@10 -- test
• npm exec --yes pnpm@10 -- type-check
• git diff --check

Note: biome check still reports the existing ResponseFormatter static-only class warning, but exits successfully after formatting.