refactor: move LSP plugin contracts to owner crates

[limityan]

Summary

• Move shared LSP protocol DTOs and plugin manifest contracts from bitfun-core to bitfun-core-types, while preserving the legacy bitfun_core::service::lsp::types import path.
• Move LSP plugin registry, language/extension lookup, supported-extension summary, and command placeholder target mapping to bitfun-services-core; keep plugin package IO and process lifecycle in the core compatibility adapter.
• Fix registry index ownership for overlapping plugins so unregistering an older overwritten plugin does not clear the newer plugin's active language/extension mappings.
• Add focused contract tests and boundary rules to prevent LSP DTO/registry ownership and overlapping-plugin unregister behavior from drifting.
• Update the core decomposition plan and layer guides to reflect the new LSP contract/service ownership.

Risk and compatibility

• Existing desktop LSP command response shape is unchanged.
• Existing Rust import paths through bitfun_core::service::lsp remain available via compatibility re-exports.
• Plugin loading, server path validation, process spawning, permission, ACP, and UI behavior are not intentionally changed.
• The registry fix only affects overlapping plugin mappings: the active newer plugin remains discoverable when an older overwritten plugin is unregistered.

Validation

• cargo test -p bitfun-core-types
• cargo test -p bitfun-services-core
• cargo test -p bitfun-services-core --test lsp_plugin_registry_contracts
• cargo check -p bitfun-core --no-default-features
• cargo check -p bitfun-core --features product-full
• cargo check -p bitfun-desktop
• cargo check --workspace
• cargo metadata --no-deps --format-version 1
• node scripts/check-core-boundaries.mjs
• node --test scripts/check-core-boundaries.test.mjs
• pnpm run check:repo-hygiene
• git diff --check

Known warning: Rust checks still show existing rmcp deprecation warnings in services-integrations/src/mcp/protocol/client_info.rs.