refactor: rename mcp tool to gateway target

[aidandaly24]

Description

Renames the mcp-tool resource type to gateway-target across the entire CLI codebase. This aligns the implementation with the gateway terminology used in the MCP Gateway feature — targets are
services exposed through gateways, not standalone tools.

File renames (8 files via git mv):

• AddMcpToolFlow.tsx → AddGatewayTargetFlow.tsx
• AddMcpToolScreen.tsx → AddGatewayTargetScreen.tsx
• RemoveMcpToolScreen.tsx → RemoveGatewayTargetScreen.tsx
• McpToolRenderer.ts → GatewayTargetRenderer.ts
• useAddMcpWizard.ts → useAddGatewayTargetWizard.ts
• remove-mcp-tool.ts → remove-gateway-target.ts
• add-mcp-tool.test.ts → add-gateway-target.test.ts
• remove-mcp-tool.test.ts → remove-gateway-target.test.ts

Identifier renames:

• Types: RemovableMcpTool → RemovableGatewayTarget, AddMcpToolConfig → AddGatewayTargetConfig, AddMcpToolStep → AddGatewayTargetStep
• Hooks: useAddMcpToolWizard → useAddGatewayTargetWizard, useRemovableMcpTools → useRemovableGatewayTargets
• Components: AddMcpToolFlow → AddGatewayTargetFlow, AddMcpToolScreen → AddGatewayTargetScreen, RemoveMcpToolScreen → RemoveGatewayTargetScreen
• Functions: renderMcpToolTemplate → renderGatewayTargetTemplate, handleAddMcpTool → handleAddGatewayTarget, removeMcpTool → removeGatewayTarget
• Command registrations: .command('mcp-tool') → .command('gateway-target')
• HIDDEN_SUBCOMMANDS: 'mcp-tool' → 'gateway-target'
• McpGuidedEditor.tsx: toolName label → targetName

Not renamed (these refer to the MCP protocol, not the tool/target concept):

• McpGuidedEditor, McpSpec, McpDefs, AgentCoreMcp — protocol-level names stay as-is
• mcp/ directory name — unchanged

Zero mcp-tool or McpTool references remain in src/cli/.

Depends on #[schema PR number].

Related Issue

Closes #

Documentation PR

N/A — internal rename only, no user-facing documentation impact.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe): Refactor — terminology rename from mcp-tool to gateway-target

Testing

How have you tested the change?

• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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