dream_observation: reorder select_mode so 3-day staleness wins over the quiet rule

Bug: the previous order checked the "nothing changed → return None" rule
first, so the spec's "corpus unchanged 3+ days → Late REM (shake things
loose)" branch could never fire. Stasis was permanent — quiet would just
keep returning None forever as long as no new chunks or journals appeared,
regardless of how stale the corpus got.

Fix: check staleness first. Quiet remains the default within the 1-2-day
window the spec implicitly grants for the dreamer to "go quiet rather than
manufacturing novelty." At day 3+, Late REM fires automatically — the
spec's mechanism for breaking out of the silence when the corpus isn't
delivering new material.

Observed symptom that triggered this: dreamer fired 2026-05-21 08:00 and
2026-05-22 08:00, both went quiet. Real cause was no new content (which
is correct quiet behavior for days 1-2), but the bug would have made it
stay quiet indefinitely had we not fixed it before day 3.

scripts/dream_observation.py

@@ -209,9 +209,14 @@ def select_mode(signal, task=None, explicit_mode=None):
     new_journal = signal["new_journal_entries"]
     days_since = signal["days_since_dream"]
 
-    # Spec line 67: nothing changed → quiet
-    if new_chunks < NEW_CHUNK_THRESHOLD and not new_journal:
-        return None
+    # Spec line 72: corpus unchanged ≥3 days → Late REM ("shake things loose").
+    # This rule has to win against the "go quiet" rule below — the spec uses
+    # quiet as the default for 1-2 days of silence, then deliberately fires
+    # Late REM at 3+ days to break the stasis. Checking staleness first is
+    # what implements that intent. (Previous version checked "go quiet" first
+    # and never reached this branch.)
+    if days_since >= STALENESS_TRIGGER_DAYS:
+        return "late-rem"
 
     # Spec line 71: journal entry → Early REM
     # We treat "any new journal entry" as the trigger. Refining to detect
@@ -220,9 +225,9 @@ def select_mode(signal, task=None, explicit_mode=None):
     if new_journal:
         return "early-rem"
 
-    # Spec line 72: corpus unchanged 3+ days → Late REM
-    if days_since >= STALENESS_TRIGGER_DAYS:
-        return "late-rem"
+    # Spec line 67: nothing changed within the staleness window → quiet
+    if new_chunks < NEW_CHUNK_THRESHOLD and not new_journal:
+        return None
 
     # Default: new chunks above threshold → NREM
     return "nrem"