[Story] Replace TooManyToolsWarning with DynamicToolsStatus indicator

[edelauna]

Context

Once dynamic loading is active (#578), the existing "Too many tools enabled" warning is wrong — most users will never see >50 tools attached at once, because that's the point. The warning is also actively misleading: it surfaces as a problem when the system is working as designed. Replace it with a positive status indicator.

Depends on #578. Partially closes: RooCodeInc/Roo-Code#11155.

Developer Notes

• Replace `webview-ui/src/components/chat/TooManyToolsWarning.tsx` with `DynamicToolsStatus.tsx` in the same slot.
• New hook `useDynamicToolStatus()` returning `{ attachedCount, totalScoped, mode: "all" | "dynamic" }`, sourced from the state slice [Story] Threshold gate and Task.attachedMcpToolNames #578 publishes (the API tools array length is already known per turn).
• Render rules:
  • `mode === "all"` (under threshold): render nothing.
  • `mode === "dynamic"`: render "N of M MCP tools attached this turn" with a click-through that expands to list the attached tool names.
• Remove i18n strings tied to the old warning (`chat.tooManyTools.*`); add new strings for the status indicator.
• Delete `TooManyToolsWarning.tsx` and the `useTooManyTools` hook.

Acceptance Criteria

• With fewer tools than threshold: no indicator visible
• With dynamic loading active: indicator shows accurate attached/total counts
• Click-through expands to list currently attached MCP tools
• Old `TooManyToolsWarning` component and hook deleted
• i18n strings updated