Finish eliminating remaining ANT-ONLY source labels (#360)

This extends the label-only cleanup to the remaining internal-only command,
debug, and heading strings so the source tree no longer contains ANT-ONLY
markers. The pass still avoids logic changes and only renames labels shown
in internal or gated surfaces.

Constraint: Update the existing label-cleanup PR without widening scope into behavior changes
Rejected: Leave the last ANT-ONLY strings for a later pass | low-cost cleanup while the branch is already focused on labels
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: The next phase should move off label cleanup and onto a separately scoped logic or rebrand slice
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/services/PromptSuggestion/speculation.ts

@@ -302,7 +302,7 @@ function createSpeculationFeedbackMessage(
       : ''
 
   return createSystemMessage(
-    `[ANT-ONLY] ${parts.join(' · ')} · ${savedText}${sessionSuffix}`,
+    `[internal-only] ${parts.join(' · ')} · ${savedText}${sessionSuffix}`,
     'warning',
   )
 }

src/services/analytics/firstPartyEventLogger.ts

@@ -186,7 +186,7 @@ async function logEventTo1PAsync(
     // Debug logging when debug mode is enabled
     if (process.env.USER_TYPE === 'ant') {
       logForDebugging(
-        `[ANT-ONLY] 1P event: ${eventName} ${jsonStringify(metadata, null, 0)}`,
+        `[internal-only] 1P event: ${eventName} ${jsonStringify(metadata, null, 0)}`,
       )
     }
 
@@ -287,7 +287,7 @@ export function logGrowthBookExperimentTo1P(
 
   if (process.env.USER_TYPE === 'ant') {
     logForDebugging(
-      `[ANT-ONLY] 1P GrowthBook experiment: ${data.experimentId} variation=${data.variationId}`,
+      `[internal-only] 1P GrowthBook experiment: ${data.experimentId} variation=${data.variationId}`,
     )
   }