feat(issues): add dependency management commands

Add commands to manage issue dependencies using the Gitea API:
- `tea issues dependencies <index>` - list dependencies
- `tea issues dependencies add <index> <dep>` - add a dependency
- `tea issues dependencies remove <index> <dep>` - remove a dependency

Supports cross-repo dependencies with owner/repo#index syntax.
Supports all output formats (table, json, csv, etc.).

Closes #4

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

modules/api/types.go

@@ -57,3 +57,10 @@ type ActionJobList struct {
 	TotalCount int64        `json:"total_count"`
 	Jobs       []*ActionJob `json:"jobs"`
 }
+
+// IssueDependencyRequest is the request body for adding/removing issue dependencies
+type IssueDependencyRequest struct {
+	Owner string `json:"owner"`
+	Repo  string `json:"repo"`
+	Index int64  `json:"index"`
+}