feat: extract @nadle/project package for project discovery and workspace scanning

[nam-hle]

Context

Follow-up to #533 (@nadle/kernel) and #536 (tracking issue). The @nadle/kernel package (Layer 1) provides pure resolution primitives. This issue covers Layer 2: extracting project discovery and workspace scanning from packages/nadle into a reusable @nadle/project package.

Currently, only packages/nadle (the CLI) can discover workspaces and build a project model. The language server operates in isolation per-document with zero project awareness — it can't resolve workspace-qualified references (shared:build), can't validate cross-file dependencies, and can't offer completions from other workspace config files.

What to extract from nadle core

Logic	Current location	What it does
Root detection	core/options/project-resolver.ts:76-121	Find monorepo root via nadle.root: true in package.json, fallback to lock file detection (@manypkg/find-root)
Workspace discovery	core/options/project-resolver.ts:76-121	Read pnpm-workspace.yaml / package.json workspaces field via @manypkg/tools to enumerate all workspaces
Config file location	core/options/project-resolver.ts:46-74	For each workspace, scan for nadle.config.{js,ts,mjs,mts} (first match wins)
Workspace metadata	core/models/project/workspace.ts, root-workspace.ts	Build { id, label, relativePath, absolutePath, configFilePath, packageJson } per workspace using kernel's deriveWorkspaceId()
Dependency resolution	core/models/project/dependency-resolver/*.ts	Scan package.json for workspace:* deps (pnpm/yarn) or matching versions (npm) to build workspace dependency graph
Alias resolution	core/models/project/alias-resolver.ts	Map workspace paths to human-readable labels via config
Validation	core/models/project/project.ts:88-111	Validate workspace labels (non-empty, no duplicates, no ID conflicts)

Package design

packages/project/
  src/
    index.ts              # Public API exports
    project-discovery.ts  # findProjectRoot(), discoverWorkspaces()
    config-locator.ts     # locateConfigFiles()
    dependency-resolver.ts # resolveWorkspaceDependencies()
    types.ts              # ProjectInfo, WorkspaceInfo interfaces
  package.json            # deps: @nadle/kernel, @manypkg/find-root, @manypkg/tools, find-up
  tsconfig.build.json

Public API

// Types
interface WorkspaceInfo {
  id: string;
  label: string;
  relativePath: string;
  absolutePath: string;
  dependencies: string[];
  packageName: string;
  packageVersion: string | undefined;
  configFilePath: string | null;
}

interface ProjectInfo {
  rootDir: string;
  packageManager: "pnpm" | "npm" | "yarn";
  rootConfigFilePath: string | null;
  workspaces: WorkspaceInfo[];
}

// Discovery
function findProjectRoot(startDir: string): Promise<string>;
function discoverWorkspaces(rootDir: string): Promise<ProjectInfo>;
function locateConfigFiles(project: ProjectInfo): Promise<ProjectInfo>;
function resolveWorkspaceDependencies(project: ProjectInfo): ProjectInfo;

Dependencies

• @nadle/kernel — workspace ID derivation, constants
• @manypkg/find-root — fallback monorepo root detection
• @manypkg/tools — workspace enumeration (pnpm, npm, yarn)
• find-up — upward directory search

Consumer changes

Language server (packages/language-server)

The biggest beneficiary. With project awareness, the LSP can:

1. On initialization: discover the project root and all workspaces
2. Eagerly scan all workspace nadle.config.* files (not just open documents)
3. Cross-file go-to-definition: resolve dependsOn: ["shared:build"] to the task registration in packages/shared/nadle.config.ts
4. Cross-file completions: when typing in a dependsOn string, suggest tasks from all workspaces
5. Workspace-qualified reference validation: verify that shared:build actually exists in the shared workspace
6. Hover info enrichment: show which workspace a referenced task belongs to

nadle core (packages/nadle)

Refactor ProjectResolver and Project to delegate to @nadle/project for discovery, keeping only nadle-specific concerns (config loading via jiti, AsyncLocalStorage binding, task registration).

IntelliJ plugin (separate repo)

Can consume @nadle/project via a Kotlin/JVM port or a Node.js bridge process.

Acceptance criteria

• @nadle/project package with the API above
• nadle core refactored to use @nadle/project for discovery
• Language server uses @nadle/project for workspace-aware features
• Unit tests for project discovery, workspace enumeration, dependency resolution
• Integration test: discover workspaces in packages/sample-app

Part of #536