Reduce internal-only labeling noise in source comments (#355)

This pass rewrites comment-only ANT-ONLY markers to neutral internal-only
language across the source tree without changing runtime strings, flags,
commands, or protocol identifiers. The goal is to lower obvious internal
prose leakage while keeping the diff mechanically safe and easy to review.

Constraint: Phase B is limited to comments/prose only; runtime strings and user-facing labels remain deferred
Rejected: Broad search-and-replace across strings and command descriptions | too risky for a prose-only pass
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Remaining ANT-ONLY hits are mostly runtime/user-facing strings and should be handled separately from comment cleanup
Tested: bun run build
Tested: bun run smoke
Tested: bun run verify:privacy
Tested: bun run test:provider
Tested: bun run test:provider-recommendation
Not-tested: Full repo typecheck (upstream baseline remains noisy)

Co-authored-by: anandh8x <test@example.com>

src/utils/thinking.ts

@@ -1,4 +1,4 @@
-// biome-ignore-all assist/source/organizeImports: ANT-ONLY import markers must not be reordered
+// biome-ignore-all assist/source/organizeImports: internal-only import markers must not be reordered
 import type { Theme } from './theme.js'
 import { feature } from 'bun:bundle'
 import { getFeatureValue_CACHED_MAY_BE_STALE } from '../services/analytics/growthbook.js'