docs(openspec): add FN-007 Git Connection Model change

- Add proposal, design, specs, and tasks for git connection model
- Include provider adapter, credential storage, SSH key lifecycle specs
- Add repository connection API and git operations specifications

openspec/changes/git-connection-model/specs/git-operations/spec.md

@@ -0,0 +1,29 @@
+## ADDED Requirements
+
+### Requirement: Git clone uses SSH credentials
+The system SHALL clone repositories using SSH keys.
+
+#### Scenario: Clone repository
+- **WHEN** the system clones a repository
+- **THEN** it writes the SSH private key to a temporary file
+- **AND** sets GIT_SSH_COMMAND to use the key
+- **AND** executes git clone
+- **AND** cleans up the temporary key file
+
+#### Scenario: Clone fails with invalid key
+- **WHEN** a clone operation fails due to authentication
+- **THEN** the system returns a clear error message
+- **AND** suggests checking deploy key permissions
+
+### Requirement: Git fetch and push use credentials
+The system SHALL support fetch and push operations with SSH credentials.
+
+#### Scenario: Fetch updates
+- **WHEN** the system fetches from a remote
+- **THEN** it uses the stored SSH key for authentication
+- **AND** returns the fetch result
+
+#### Scenario: Push changes
+- **WHEN** the system pushes to a remote
+- **THEN** it uses the stored SSH key for authentication
+- **AND** returns the push result