fix(myorg-assistant): inject WEB_SECRET_KEY into all cronjobs

CronJob containers import src.config.Settings() at startup, which requires
WEB_SECRET_KEY. Only the Deployment set it; the 5 CronJobs (git-sync,
morning-briefing, evening-summary, waiting-followup, deadline-checker) crashed
at import with a pydantic ValidationError, causing restart loops (e.g.
myorg-git-sync ~5 restarts/15m). Pull WEB_SECRET_KEY from the existing
myorg-assistant-secret so the cronjobs start cleanly.

myorg-assistant/cronjobs/deadline-checker.yaml

@@ -53,6 +53,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: myorg-assistant-secret
+                  key: LITELLM_API_KEY
             - name: WEB_SECRET_KEY
               valueFrom:
                 secretKeyRef:

myorg-assistant/cronjobs/evening-summary.yaml

@@ -53,6 +53,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: myorg-assistant-secret
+                  key: LITELLM_API_KEY
             - name: WEB_SECRET_KEY
               valueFrom:
                 secretKeyRef:

myorg-assistant/cronjobs/git-sync.yaml

@@ -68,6 +68,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: myorg-assistant-secret
+                  key: LITELLM_API_KEY
             - name: WEB_SECRET_KEY
               valueFrom:
                 secretKeyRef:

myorg-assistant/cronjobs/morning-briefing.yaml

@@ -60,6 +60,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: myorg-assistant-secret
+                  key: LITELLM_API_KEY
             - name: WEB_SECRET_KEY
               valueFrom:
                 secretKeyRef:

myorg-assistant/cronjobs/waiting-followup.yaml

@@ -53,6 +53,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: myorg-assistant-secret
+                  key: LITELLM_API_KEY
             - name: WEB_SECRET_KEY
               valueFrom:
                 secretKeyRef: