Fix all Kind 11125 write paths to preserve profile content JSON

Critical safety fix: 9 out of 12 Kind 11125 publish paths were
hardcoding content: '' which would silently erase any structured
content (daily missions data) stored in the profile event.

Every write path that updates an existing profile now preserves
the existing event content via profile.event.content instead of
overwriting with empty string.

Fixed locations:
- useBlobbiOnboarding.ts: reroll preview (line 378) and adopt (476)
- BlobbiHatchingCeremony.tsx: add egg to has[] (302) and mark
  onboarding done (501)
- useBlobbiMigration.ts: legacy migration (190)
- useBlobbonautProfileNormalization.ts: tag normalization (85)
- BlobbiPage.tsx: auto-fix onboardingDone (547) and companion
  toggle (1183)
- useBlobbiPurchaseItem.ts: shop purchase (89)

The only two paths that still use content: '' are initial profile
creation flows (useBlobbiOnboarding auto-create and
BlobbiHatchingCeremony silent setup) where no previous event exists.

The useClaimMissionReward path already uses mergeProfileContent
for proper read-modify-write of the content JSON.

src/blobbi/core/hooks/useBlobbiMigration.ts

@@ -188,7 +188,7 @@ export function useBlobbiMigration() {
       
       const profileEvent = await publishEvent({
         kind: KIND_BLOBBONAUT_PROFILE,
-        content: '',
+        content: profile.event.content,
         tags: profileTags,
       });
       

src/blobbi/onboarding/components/BlobbiHatchingCeremony.tsx

@@ -300,7 +300,7 @@ export function BlobbiHatchingCeremony({
 
           const updatedProfileEvent = await publishEvent({
             kind: KIND_BLOBBONAUT_PROFILE,
-            content: '',
+            content: currentProfile?.event.content ?? '',
             tags: updatedTags,
           });
 
@@ -499,7 +499,7 @@ export function BlobbiHatchingCeremony({
         });
         const profileEvent = await publishEvent({
           kind: KIND_BLOBBONAUT_PROFILE,
-          content: '',
+          content: currentProfile.event.content,
           tags: updatedTags,
         });
         updateProfileEvent(profileEvent);

src/blobbi/onboarding/hooks/useBlobbiOnboarding.ts

@@ -376,7 +376,7 @@ export function useBlobbiOnboarding({
       
       const profileEvent = await publishEvent({
         kind: KIND_BLOBBONAUT_PROFILE,
-        content: '',
+        content: profile.event.content,
         tags: updatedTags,
       });
       
@@ -474,7 +474,7 @@ export function useBlobbiOnboarding({
       
       const profileEvent = await publishEvent({
         kind: KIND_BLOBBONAUT_PROFILE,
-        content: '',
+        content: profile.event.content,
         tags: updatedProfileTags,
       });
       

src/blobbi/shop/hooks/useBlobbiPurchaseItem.ts

@@ -87,7 +87,7 @@ export function useBlobbiPurchaseItem(currentProfile: BlobbonautProfile | null)
       // Publish updated profile event
       const event = await publishEvent({
         kind: KIND_BLOBBONAUT_PROFILE,
-        content: '',
+        content: currentProfile.event.content,
         tags: updatedTags,
       });
 

src/hooks/useBlobbonautProfileNormalization.ts

@@ -83,7 +83,7 @@ export function useBlobbonautProfileNormalization({
         // Always publish to the NEW kind (11125), regardless of source kind
         const event = await publishEvent({
           kind: KIND_BLOBBONAUT_PROFILE,
-          content: '',
+          content: profile.event.content,
           tags: normalizedTags,
         });
         

src/pages/BlobbiPage.tsx

@@ -545,7 +545,7 @@ function BlobbiContent() {
         });
         publishEvent({
           kind: KIND_BLOBBONAUT_PROFILE,
-          content: '',
+          content: profile.event.content,
           tags: updatedTags,
         }).then(event => {
           updateProfileEvent(event);
@@ -1181,7 +1181,7 @@ function BlobbiDashboard({
       
       const event = await publishEvent({
         kind: KIND_BLOBBONAUT_PROFILE,
-        content: '',
+        content: profile.event.content,
         tags: updatedTags,
       });