Add changeset for project config and schema commands (Fission-AI#530)

Author: TabishB

.changeset/project-config-schema-commands.md

@@ -0,0 +1,15 @@
+---
+"@fission-ai/openspec": minor
+---
+
+### New Features
+
+- **Project-level configuration** — Configure OpenSpec behavior per-project via `openspec/config.yaml`, including custom rules injection, context files, and schema resolution settings
+
+- **Project-local schemas** — Define custom artifact schemas within your project's `openspec/schemas/` directory for project-specific workflows
+
+- **Schema management commands** — New `openspec schema` commands (`list`, `show`, `export`, `validate`) for inspecting and managing artifact schemas (experimental)
+
+### Bug Fixes
+
+- Fixed config loading to handle null `rules` field in project configuration