fix(site): align React Compiler check scope with vite.config.mts (#27216)

## Stack Context

First PR of a 6-PR stack that thins the agent instruction corpus (~4,800
lines down to ~2,800) by removing startup bloat, assigning each
procedure one canonical owner, and fixing rules that drifted from
reality. Split from #27203 for reviewability.

## Why?

`site/vite.config.mts` compiles `src/pages/AIBridgePage/` with the React
Compiler, but `site/scripts/check-compiler.mjs` did not include that
directory. Compiler regressions in AIBridgePage were invisible to CI:
code could silently bail out of compilation with no signal. The two
lists had already drifted once, which is exactly how this class of bug
recurs.

## What?

- Add `src/pages/AIBridgePage/` to the check-compiler scope. Verified
all 381 functions in scope compile cleanly.
- Cross-reference the two lists with comments so the next person who
edits one finds the other.

This is the only behavioral (non-docs) change in the stack, which is why
it sits at the bottom.

> This PR was prepared by Mux (AI agent) on Mike's behalf.

site/scripts/check-compiler.mjs

@@ -16,10 +16,11 @@ import { transformSync } from "@babel/core";
 // Resolve the site/ directory (ESM equivalent of __dirname + "..").
 const siteDir = new URL("..", import.meta.url).pathname;
 
-// Only AgentsPage is currently opted in to React Compiler. Add new
-// directories here as more pages are migrated.
+// Directories opted in to React Compiler. Keep this list in sync with
+// the include filter in vite.config.mts.
 const targetDirs = [
 	"src/pages/AgentsPage",
+	"src/pages/AIBridgePage",
 ];
 
 const skipPatterns = [".test.", ".stories.", ".jest."];