fix(lsp): keep JDTLS alive during active project import

[1lck]

Summary

• split the standard LSP initialize deadline from JDTLS ServiceReady project-import readiness in shared Rust Core
• use a 45-second no-progress timeout plus a 10-minute absolute cap, while meaningful module and download progress keeps the session alive
• emit structured module, download, throughput, cache, elapsed-time, and stall diagnostics for Windows and macOS
• remove Windows frontend-owned readiness deadlines and keep both platforms dependent on Core lifecycle events
• disable nonessential Maven and Eclipse source attachment downloads during initial import while retaining required POM and JAR resolution

Validation

• ./scripts/verify-rust-core.sh
• ./scripts/verify-shared-contracts.sh
• ./scripts/verify-windows-boundaries.sh
• ./scripts/verify-service-boundaries.sh
• ./scripts/test-macos.sh
• bun test src/platform/lsp-core-adapter.test.ts src/features/editor/lsp/java-workspace-language-server.test.ts
• bun run typecheck

Rust Core: 262 tests passed. macOS: 659 tests in 77 suites passed. Windows targeted tests: 20 passed.