feat(memory): ambient nudges for record_decision and record_code_area

[rajkumarsakthivel]

Summary

CCE's cross-session memory depends on the agent calling record_decision and record_code_area, but that only happens when the agent obeys CLAUDE.md instructions. If context compacts or the agent just forgets, the session produces no durable memory. This PR makes recording ambient by nudging the agent from within tool results.

Inline nudges on context_search:

• Decision nudge fires after 4 context searches with 0 decisions recorded this session. Message includes the search count and a directive to call record_decision if a non-obvious choice was made. Includes "skip if this session is just exploration/reading" to prevent garbage recordings. After the first record_decision, the threshold doubles to 8 (longer leash once the agent has shown it knows how).

• Code area nudge fires when 3+ files have been explored (via context_search or expand_chunk) without any record_code_area call. Lists the specific unrecorded file paths (max 5) so the agent has concrete material to act on rather than a generic reminder. Files that were already record_code_area'd are excluded from the count.

Both nudges can fire in the same response. They appear before the output compression directive, as part of the tool result text.

Stop hook summary:

The existing Stop hook (fires on session end) now returns a compact summary: search count, decisions recorded, code areas recorded, with a directive to record if counts are low. The hook script is updated to capture Stop stdout (previously only SessionStart output was captured). Users get the updated script on next cce init.

Example nudge (after 4th search, 0 decisions):

[CCE] 4 context searches this session, 0 decision(s) recorded.
If you chose a library, resolved an ambiguity, or established a convention, call record_decision(decision="...", reason="...").
Skip if this session is just exploration/reading.

Example code area nudge:

[CCE] 3 files explored but not recorded: src/auth.py, src/middleware.py, src/routes.py
If you modified or traced a non-obvious flow, call record_code_area(file_path="...", description="...").
Skip for files you only glanced at.