feat: improve memory prioritization + aggressive skill updates (inspired by OpenAI Codex)

* feat: improve memory prioritization — user preferences over procedural knowledge

Inspired by OpenAI Codex's memory prompt improvements (openai/codex#14493)
which focus memory writes on user preferences and recurring patterns
rather than procedural task details.

Key insight: 'Optimize for reducing future user steering — the most
valuable memory prevents the user from having to repeat themselves.'

Changes:
- MEMORY_GUIDANCE (prompt_builder.py): added prioritization hierarchy
  and the core principle about reducing user steering
- MEMORY_SCHEMA (memory_tool.py): reordered WHEN TO SAVE list to put
  corrections first, added explicit PRIORITY guidance
- Memory nudge (run_agent.py): now asks specifically about preferences,
  corrections, and workflow patterns instead of generic 'anything'
- Memory flush (run_agent.py): now instructs to prioritize user
  preferences and corrections over task-specific details

* feat: more aggressive skill creation and update prompting

Press harder on skill updates — the agent should proactively patch
skills when it encounters issues during use, not wait to be asked.

Changes:
- SKILLS_GUIDANCE: 'consider saving' → 'save'; added explicit instruction
  to patch skills immediately when found outdated/wrong
- Skills header: added instruction to update loaded skills before finishing
  if they had missing steps or wrong commands
- Skill nudge: more assertive ('save the approach' not 'consider saving'),
  now also prompts for updating existing skills used in the task
- Skill nudge interval: lowered default from 15 to 10 iterations
- skill_manage schema: added 'patch it immediately' to update triggers

tools/skill_manager_tool.py

@@ -561,7 +561,8 @@ SKILL_MANAGE_SCHEMA = {
         "user-corrected approach worked, non-trivial workflow discovered, "
         "or user asks you to remember a procedure.\n"
         "Update when: instructions stale/wrong, OS-specific failures, "
-        "missing steps or pitfalls found during use.\n\n"
+        "missing steps or pitfalls found during use. "
+        "If you used a skill and hit issues not covered by it, patch it immediately.\n\n"
         "After difficult/iterative tasks, offer to save as a skill. "
         "Skip for simple one-offs. Confirm with user before creating/deleting.\n\n"
         "Good skills: trigger conditions, numbered steps with exact commands, "