feat: Restore "WHEN TO SKIP" guidance to continuation prompt

Restores observation skip guidance that was removed in commit 68290a9
for token reduction. The removal caused the observer agent to forget
skip criteria after the first prompt, leading to more verbose
observations of routine operations.

Changes:
- Added WHEN TO SKIP section back to buildContinuationPrompt
- Added condensed CRITICAL reminder about what to record
- Maintains token efficiency by using condensed guidance vs full examples

This balances token usage with observation quality by keeping the
essential skip criteria without the full WHAT TO RECORD examples.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/sdk/prompts.ts

@@ -233,6 +233,18 @@ Hello memory agent, you are continuing to observe the primary Claude session.
 
 You do not have access to tools. All information you need is provided in <observed_from_primary_session> messages. Create observations from what you observe - no investigation needed.
 
+CRITICAL: Record what was LEARNED/BUILT/FIXED/DEPLOYED/CONFIGURED, not what you (the observer) are doing. Focus on deliverables and capabilities - what the system NOW DOES differently.
+
+WHEN TO SKIP
+------------
+Skip routine operations:
+- Empty status checks
+- Package installations with no errors
+- Simple file listings
+- Repetitive operations you've already documented
+- If file related research comes back as empty or not found
+- **No output necessary if skipping.**
+
 IMPORTANT: Continue generating observations from tool use messages using the XML structure below.
 
 OUTPUT FORMAT