chore: link to audit docs and add prompt attribution tooltip on AI Bridge sessions page (#23969)

*Disclaimer: implemented by a Coder Agent using Claude Opus 4.6*

## Summary

Two changes on the AI Bridge sessions page
(`/aibridge/sessions/<session>`):

1. **Updated header subtitle and link** — replaced the generic
"Centralized auditing for LLM usage across your organization. More about
AI Governance" with auditing-specific copy and a link to the [AI Bridge
audit docs](https://coder.com/docs/ai-coder/ai-bridge/audit).

2. **Added prompt attribution tooltip** — each user prompt now shows an
info icon with a tooltip explaining that prompt origin cannot be
reliably determined (human vs. agent), linking to the [attribution
docs](https://coder.com/docs/ai-coder/ai-bridge/audit#human-vs-agent-attribution).

## Changes

| File | What changed |
|------|-------------|
| `AIBridgeSessionsLayout.tsx` | Updated subtitle text and link target |
| `SessionTimeline.tsx` | Added `InfoIcon` + `Tooltip` next to the
"Prompt" label in `ThreadItem` |

<img width="954" height="318" alt="image"
src="https://github.com/user-attachments/assets/db3ca443-cb0f-426a-8457-4625c82fd6ba"
/>

---------

Signed-off-by: Danny Kopping <danny@coder.com>

site/src/pages/AIBridgePage/AIBridgeSessionsLayout.tsx

@@ -19,13 +19,14 @@ const AIBridgeSessionsLayout: FC<PropsWithChildren> = () => {
 					</div>
 				</PageHeaderTitle>
 				<PageHeaderSubtitle>
-					Centralized auditing for LLM usage across your organization.{" "}
+					Review and audit AI activity, token usage, and prompt history across
+					sessions.{" "}
 					<Link
-						href={docs("/ai-coder/ai-governance")}
+						href={docs("/ai-coder/ai-bridge/audit")}
 						className="ml-auto"
 						target="_blank"
 					>
-						More about AI Governance
+						Learn how to audit AI sessions
 					</Link>
 				</PageHeaderSubtitle>
 			</PageHeader>

site/src/pages/AIBridgePage/SessionThreadsPage/SessionTimeline/SessionTimeline.tsx

@@ -323,8 +323,34 @@ const ThreadItem: FC<ThreadItemProps> = ({ thread, initiator }) => {
 				<div className="flex-grow flex flex-col gap-1">
 					{thread.prompt && (
 						<>
-							<div className="text-sm text-content-secondary font-normal my-1">
+							<div className="text-sm text-content-secondary font-normal my-1 flex items-center gap-1">
 								Prompt
+								<TooltipProvider>
+									<Tooltip>
+										<TooltipTrigger asChild>
+											<InfoIcon className="size-icon-xs p-0.5 text-content-secondary" />
+										</TooltipTrigger>
+										<TooltipContent
+											className="max-w-96 text-sm font-normal"
+											align="start"
+											side="top"
+										>
+											<p className="text-content-secondary m-0 mb-1">
+												Prompt origin cannot be reliably determined. This may
+												have been authored by a human or generated by an agent.{" "}
+											</p>
+											<Link
+												href={docs(
+													"/ai-coder/ai-bridge/audit#human-vs-agent-attribution",
+												)}
+												target="_blank"
+												className="text-sm"
+											>
+												Learn about human vs. agent attribution
+											</Link>
+										</TooltipContent>
+									</Tooltip>
+								</TooltipProvider>
 							</div>
 							<p className="text-sm text-content-secondary font-normal bg-surface-secondary leading-relaxed rounded-md p-3 overflow-auto m-0 text-pretty">
 								{thread.prompt}
@@ -332,7 +358,6 @@ const ThreadItem: FC<ThreadItemProps> = ({ thread, initiator }) => {
 						</>
 					)}
 				</div>
-
 				{/* right column: details */}
 				<PromptTable
 					className="lg:max-w-64 flex-shrink-0 w-full lg:w-auto"