feat(scope): add opt-in user resource inheritance

[GaoSSR]

Summary

Project scope isolation prevents cross-project leakage, but it also leaves no supported way to combine organization-wide practices with project-specific resources. This adds a project-local, opt-in inheritUserScope mode that layers safe user resources and searchable knowledge while preserving project isolation by default.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature causing existing behavior to change)
• Documentation only
• Refactor / internal cleanup

Test Plan

• npx tsc --noEmit passes
• npx vitest run --coverage passes (144 files, 1907 tests)
• Added/updated tests for the change
• npm run build passes
• npx vitest run --config vitest.e2e.config.ts src/__tests__/scope-inheritance-e2e.test.ts passes (6 tests)

Related Issues

Related to #73.

Notes for Reviewers

• Default project-only behavior remains unchanged unless the local project config enables inheritance.
• The inherited channel includes skills, rules, docs, agents, shared instructions/culture, and the user search index.
• User env, hooks, MCP definitions, external sources, usage reporting, remote writes, and inherited-result vote writes remain isolated.
• Partial user sync uses lastInheritedPullRev, so it cannot suppress a later full user pull.
• Recall searches project first and shadows an identical user resource type and filename using the complete project index.
• This branch is stacked on docs(scope): align scope docs with runtime behavior #280 so the behavior documentation can merge first without creating conflicting follow-up edits.

[jeff-r2026]

Thanks for you contribution , Please solve the conflicts.

[GaoSSR]

@jeff-r2026 Thanks，I merged the latest upstream/main into this branch and resolved the documentation conflicts caused by the squash merge of #280. All checks are passing, and the PR is now mergeable.

[jeff-r2026]

LGTM