feat: workspace discovery for monorepo support

[BYK]

Problem

Lore uses process.cwd() as the project path with no directory traversal. This fails for monorepo setups:

1. Downward (primary pain point): User runs lore run from monorepo root (no .git). Sub-projects are bare directories under the root, each with their own .git and .lore.md. Lore never discovers these sub-project .lore.md files.

2. Upward: User runs from a sub-project. Lore doesn't discover the monorepo root above, missing shared config.

Solution

Config-driven sub-project discovery

New workspaces field in .lore.json:

// Bare sub-projects directly under monorepo root:
{ "workspaces": ["project-a", "project-b", "shared-lib"] }

// Standard monorepo layout:
{ "workspaces": ["packages/*"] }

// Mixed:
{ "workspaces": ["packages/*", "tools/cli", "infra"] }

Supports literal relative paths and single-level globs. Mirrors package.json workspaces / pnpm-workspace.yaml conventions.

Upward discovery via discoverWorkspaceRoot()

Walks up from cwd checking for project markers at each level:

1. .lore.json with workspaces field (strongest signal — user explicitly declared workspace root)
2. VCS markers: .git, .hg, .svn, .jj, etc. (definitive)
3. Workspace markers: pnpm-workspace.yaml, nx.json, turbo.json, etc. (definitive)
4. Language markers: package.json, pyproject.toml, Cargo.toml, etc. (closest-wins, walk continues)

Stop boundary at homedir() — never claims $HOME as workspace root even if ~/.git exists (common dotfile managers).

Integration flow

At startup (initIfNeeded):

1. Resolve project path (may walk up to find workspace root)
2. Load .lore.json from resolved path
3. If workspaces is configured, resolve glob patterns to sub-project dirs
4. Import .lore.md from each sub-project into the root project's knowledge base (via importLoreFileAs)
5. Watch sub-project .lore.md files for live changes (independent debounce timers per watcher)

Sub-project .lore.md files are read-only imports — entries are attributed to the root project so they're visible via forSession(). Lore does not write back to sub-project files.

Safety

• Path traversal guard: resolveWorkspaces rejects ../ escapes — resolved paths must be under rootDir
• Dot-prefix filtering: Glob expansion skips .git, .vscode, etc. (matches npm/pnpm behavior)
• Homedir boundary: Walk stops before checking markers at $HOME
• Hosted mode guards: Both functions return safe defaults, preventing filesystem traversal with client-controlled paths
• Mtime fast-path: importLoreFileAs skips re-import when source file unchanged (mtime cache)

Files changed

File	Change
packages/core/src/workspace.ts	NEW — discoverWorkspaceRoot() + resolveWorkspaces()
packages/core/src/config.ts	Add workspaces field to schema
packages/core/src/agents-file.ts	Add importLoreFileAs()
packages/core/src/index.ts	New exports
packages/core/test/workspace.test.ts	NEW — 31 tests
packages/gateway/src/cli/run.ts	Use discoverWorkspaceRoot(process.cwd())
packages/gateway/src/config.ts	Apply to cwd fallback
packages/gateway/src/pipeline.ts	Sub-project import at startup + file watchers
packages/opencode/src/index.ts	Apply workspace root to project path

Test plan

• 31 unit tests covering both directions of discovery + edge cases
• Typecheck clean across all 4 packages
• Existing test suites (config, agents-file, git) pass with no regressions