cleanup: fix all build warnings, delete dead DMN context code

- Delete poc-daemon/src/context.rs dead code (git_context, work_state,
  irc_digest, recent_commits, uncommitted_files) — replaced by
  where-am-i.md and memory graph
- Remove unused imports (BufWriter, Context, similarity)
- Prefix unused variables (_store, _avg_cc, _episodic_ratio, _message)
- #[allow(dead_code)] on public API surface that's not yet wired
  (Message::assistant, ConversationLog::message_count/read_all,
  Config::context_message, ContextInfo fields)
- Fix to_capnp macro dead_code warning
- Rename _rewrite_store_DISABLED to snake_case

Only remaining warnings are in generated capnp code (can't fix).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/agents/transfer.agent

@@ -1,7 +1,6 @@
 {"agent": "transfer", "query": "all | type:episodic | sort:timestamp | limit:15", "model": "sonnet", "schedule": "daily", "tools": ["Bash(poc-memory:*)"]}
 # Transfer Agent — Complementary Learning Systems
 
-
 {{node:core-personality}}
 
 {{node:memory-instructions-core}}