refactor: rename 'tool' terminology to 'agent' or 'provider'

[varkart]

Problem

The codebase uses "tool" to mean two completely different things:

Usage	Means
AiTool, tool_id, get_tools()	A coding agent/provider (Claude Code, Cursor, Windsurf…)
MCP "tools"	The callable functions an MCP server exposes

This creates confusion in code, UI copy, and user communication. A user reading "Open MCPs page" from inside a "tool" doesn't know if "tool" = the agent or the MCP function.

Proposed rename

AiTool / tool (the agent/provider) → Agent or Provider

Leaning toward Agent since the home page already calls them "Coding Agents".

Before	After
AiTool (TypeScript type)	Agent
tool_id field	agent_id
get_tools() Tauri command	get_agents()
AiToolDetector trait (Rust)	AgentDetector
selectedTool in router state	selectedAgent
tool-detail view name	agent-detail
useTools hook	useAgents
"Coding Agents" in UI (already correct)	keep

Scope

Large but mechanical rename. Touches:

• All Rust detector files (src-tauri/src/detectors/)
• Rust models, commands in lib.rs
• TypeScript types (src/types.ts)
• Router state and actions (src/viewRouter.ts)
• All React components that reference tool/AiTool
• Tests

Approach

Do in one PR — partial renames are worse than none. Use sed/find-replace for the bulk, then verify TypeScript + Rust compile clean.

Not in scope

• MCP "tool" terminology (MCP spec owns that word, we don't control it)
• UI copy changes beyond what's already labelled incorrectly

[varkart]

Completed by #91 and #90 — all tool/LLM terminology renamed to agent.