feat: use roots/list to automatically detect workspace directory

[Vaiz]

solves issue #106 for supported IDEs. It uses roots/list request to find out cwd for current project. The detection runs only once when MCP server is initialized.

the fix works for VS Code, doesn't work for Zed though - zed-industries/zed#53156

[Copilot]

Pull request overview

Adds automatic workspace root detection for the Rust MCP server by querying the MCP client’s roots/list after initialization, so tool commands can run in the project directory without requiring --workspace.

Changes:

• Introduce src/workspace.rs to detect a Cargo workspace via roots/list and apply the detected root to executed commands.
• Refactor workspace root storage from String to PathBuf and wire detection into server initialization.
• Add percent-encoding (URI decoding) and enable Tokio’s time feature for detection timeouts.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/workspace.rs	New workspace auto-detection logic + URI-to-path conversion + unit tests.
src/rmcp_server.rs	Triggers workspace detection in on_initialized behind a flag.
src/main.rs	Enables detection when --workspace isn’t provided and passes flag to server.
src/globals.rs	Stores workspace root as PathBuf and adds try_set_workspace_root.
src/command.rs	Applies workspace root from the new workspace module before running commands.
src/tools/mod.rs	Stops re-exporting apply_workspace_root (now in workspace).
src/tools/cargo/doc.rs	Updates path joining to use PathBuf root directly.
Cargo.toml	Adds percent-encoding; enables tokio time feature.
Cargo.lock	Records dependency graph changes (includes broad upgrades).
.vscode/mcp.json	Adjusts local dev config args (log level).
.github/copilot-instructions.md	Updates repo Copilot guidance text.
.github/agents/rust-docs.agent.md	Adds a rust-docs agent definition.