Add rename command

[Copilot]

• Add README documentation for rename command
• Implement rename command with validation and tests
• Move Name option from CommonOptions to RenameStackCommand (comment feedback)
• Add test for stacks with same name across different remotes (comment feedback)
• Use Questions.StackName instead of Questions.NewStackName for prompts (comment feedback)
• Add early return for no stacks found to prevent errors (comment feedback)

Features

The new command provides:

• --stack option to specify which stack to rename
• --name option to specify the new stack name
• Interactive prompts when options are not provided
• Validation to prevent duplicate stack names for the same remote
• Proper error handling for non-existent stacks
• Early exit with appropriate message when no stacks exist for the repository

Usage Examples

# Rename with prompts
stack rename

# Rename specific stack with prompts for new name
stack rename --stack "feature-branch"

# Full command without prompts
stack rename --stack "old-name" --name "new-name"

Implementation Details

• Added ChangeName method to the Stack record using immutable record pattern
• Created RenameStackCommand and RenameStackCommandHandler following existing patterns
• Added comprehensive validation to prevent naming conflicts
• Registered command in dependency injection container
• Updated CLI help and README documentation
• Moved --name option to be command-specific rather than common
• Uses consistent question text with existing Questions.StackName
• Added early return with common log message when no stacks exist for repository

Testing

Added 9 comprehensive unit tests covering:

• Interactive prompting scenarios
• Validation edge cases (duplicate names, non-existent stacks)
• Cross-remote name validation (allows same names across different remotes)
• Error handling and success paths
• No stacks found scenario

All 202 existing tests continue to pass, ensuring no regressions.

Fixes #363.

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[geofflamrock]

@copilot move this into the rename command directly, it shouldn't be common as it's not going to be used across multiple commands and is specific to the rename command.

[Copilot]

Moved the Name option from CommonOptions to RenameStackCommand as a local static option since it's only used by the rename command. This follows the same pattern as other commands like NewStackCommand that define their own specific options. (035a2d5)

[geofflamrock]

@copilot instead of using this new question, use the existing Questions.StackName. Do NOT change the question text of Questions.StackName, just use it here and fix any tests.

[Copilot]

Changed to use Questions.StackName instead of Questions.NewStackName and updated all related tests. All 201 tests continue to pass. (82f290c)