v0.3.0

release: v0.3.0 — claude.ai remote connector + prebuilt-binary pipeline

- mcp.rs: OAuth-discovery stub + Mcp-Session-Id handshake + gated SEP-973 serverInfo,
  so the claude.ai web/mobile custom connector validates and stays connected
- README accurate to the real 21-tool surface (drop phantom finance_snapshot + STOOQ;
  add finance_movers + finance_curve; FRED keyless; install ladder)
- version 0.3.0 across the workspace and crates
- .github/workflows/release.yml: cross-build prebuilt binaries (mac/linux/windows) on tag
- npm/ wrapper for npx market-search; favicon for the connector icon