Add LLM Kit documentation

[Copilot]

Introduces documentation for the Telerik UI for Blazor LLM Kit — a set of purpose-built components for building transparent, enterprise-ready AI agent UIs with visibility, human-in-the-loop control, and auditability.

New files — components/llmkit/

• overview.md — Describes the kit's purpose, lists all five components in a summary table, and includes a static combined example showing all components rendered in a completed workflow state.
• chain-of-thought.md — TelerikChainOfThought: typed step list with ThoughtTemplate, Expandable, Completed.
• checkpoint.md — TelerikCheckpoint: restore point with State / StateChanged.
• citation.md — TelerikCitation: inline source chip with Data, TItem, Label.
• tool-call.md — TelerikToolCall: tool invocation display with parameters, result, and approval flow via ToolCallState / OnAction.
• reasoning.md — TelerikReasoning: collapsible agent scratchpad with Content template, Completed, SecondaryLabel.

Conventions followed

• Each article has a minimal, self-contained static demo — no timers or state machines.
• Parameter documentation deferred to API reference links (SegmentedControl pattern) rather than inline tables.
• Cross-links between all articles and back to the overview.

[IvanDanchev]

@copilot
The Reasoning component's tag is now . Replace it in the overview and reasoning articles.

[Copilot]

@copilot
The Reasoning component's tag is now . Replace it in the overview and reasoning articles.

It looks like your comment got cut off before the sentence finished. Could you complete your feedback so I can address it?

[IvanDanchev]

@copilot
The Reasoning component's

<Content> 

tag is now

<ContentTemplate>

Replace it in the overview and reasoning articles.

[Copilot]

@copilot
The Reasoning component's

...

Done — replaced <Content> with <ContentTemplate> in both reasoning.md and overview.md in commit Replace Content tag with ContentTemplate in Reasoning docs.