## Why

CLAUDE.md currently holds all project knowledge — description, constraints, and a large tech stack research block. With OpenSpec initialized, this content belongs in `openspec/specs/` where it can be managed as proper specs, referenced by changes, and won't conflict with CLAUDE.md's role as a slim workflow/instruction file.

## What Changes

- Extract project description and constraints into a `project` spec
- Extract full technology stack research into a `stack` spec
- Populate `openspec/config.yaml` with project context
- Slim CLAUDE.md down to workflow instructions with pointers to OpenSpec
- Remove stale GSD placeholder sections (conventions, architecture, profile)

## Capabilities

### New Capabilities
- `project`: Project identity, core value statement, and non-negotiable constraints
- `stack`: Technology stack decisions — packages, versions, alternatives, patterns, compatibility, and sources

### Modified Capabilities
<!-- None — no existing specs yet -->

## Impact

- `CLAUDE.md`: Reduced from ~147 lines to a slim pointer file
- `openspec/specs/project/spec.md`: New file with project identity
- `openspec/specs/stack/spec.md`: New file with stack research
- `openspec/config.yaml`: Updated with project context