refactor(dream): replace two-phase Dream class with simple cron + process_direct (#3990)

* refactor(dream): replace two-phase Dream class with simple cron + process_direct

- Remove the heavyweight Dream class (AgentRunner-based two-phase system)
  from nanobot/agent/memory.py
- Delete dream_phase1.md and dream_phase2.md templates
- New dream.md template serves as the consolidation prompt
- Cron callback uses agent.process_direct(prompt, session_key=\"dream\")
  instead of agent.dream.run()
- Always performs git auto_commit after execution
- /dream command updated to use process_direct + git commit
- DreamConfig kept for backward compatibility; deprecated fields
  (model_override, max_batch_size, max_iterations, annotate_line_ages)
  are ignored but accepted in config
- interval_h remains configurable via agents.defaults.dream.interval_h
- Update tests and webui settings to match new architecture

* feat(loop): add ephemeral mode to process_direct, skip history writes for Dream

When ephemeral=True, _state_save skips enforce_file_cap (which calls
raw_archive -> append_history) and consolidator.maybe_consolidate_by_tokens.
This prevents Dream sessions from creating a positive feedback loop where
they process their own output. The session IS still saved to disk.

* fix(loop): skip extra hooks for ephemeral sessions (Dream)

* feat(dream): per-run timestamped sessions with rotation for WebUI

* test(config): restore DreamConfig schedule and alias tests

* fix(dream): include LLM response summary in git auto-commit message

The old two-phase Dream class included the Phase 1 analysis in the git
commit message body. The new single-phase version lost this. Restore it
by extracting resp.content from the process_direct return value and
appending it to the commit message in both the cron handler and the
/dream command.

* fix(test): accept ephemeral kwarg in test_openai_api fake_process

* refactor(dream): merge dream_session.py into MemoryStore

The standalone dream_session.py module only contained three small helpers
that all revolve around MemoryStore concerns (session keys, commit messages,
file pruning). Fold them into MemoryStore as @staticmethod to reduce
indirection and avoid a 35-line module with no independent reason to exist.

* fix(test): address code review — patch correct instance, use actual function

- Fix test_ephemeral_skips_raw_archive to patch loop.context.memory
  instead of the fixture's separate MemoryStore instance
- Fix TestDreamCommitMessage to call MemoryStore.build_dream_commit_message
  instead of reimplementing the logic inline
- Move Dream helpers in memory.py above the Consolidator section comment
  to avoid misleading visual boundary

* fix(dream): gate cursor advancement and restrict tools

maintainer edit: Dream now processes backlog from the oldest unprocessed entries, only advances the cursor after a completed ephemeral run, and uses a restricted file-only tool registry for background consolidation.

* fix(dream): skip idle compact for dream sessions

Dream runs use internal dream:* sessions that are pruned by Dream retention. Exclude them from AutoCompact scheduling, archive execution, and summary injection so idle-session compaction cannot truncate Dream transcripts.

* fix(dream): keep batched history isolated

* feat(dream): tag archived memory for single-phase Dream

---------

Co-authored-by: Xubin Ren <52506698+Re-bin@users.noreply.github.com>

tests/cli/test_commands.py

@@ -1607,14 +1607,6 @@ def test_gateway_health_endpoint_binds_and_serves_expected_responses(
     config.gateway.port = 18791
     captured: dict[str, object] = {}
 
-    class _FakeDream:
-        model = None
-        max_batch_size = 0
-        max_iterations = 0
-
-        async def run(self) -> None:
-            return None
-
     class _FakeSessionManager:
         def flush_all(self) -> int:
             return 0
@@ -1626,7 +1618,6 @@ def test_gateway_health_endpoint_binds_and_serves_expected_responses(
         def __init__(self, **_kwargs) -> None:
             self.model = "test-model"
             self.provider = object()
-            self.dream = _FakeDream()
             self.sessions = _FakeSessionManager()
 
         def llm_runtime(self) -> None: