cli: extract agent and admin commands from main.rs

Move agent handlers (consolidate, replay, digest, experience-mine,
fact-mine, knowledge-loop, apply-*) into cli/agent.rs.

Move admin handlers (init, fsck, dedup, bulk-rename, health,
daily-check, import, export) into cli/admin.rs.

Functions tightly coupled to Clap types (cmd_daemon, cmd_digest,
cmd_apply_agent, cmd_experience_mine) remain in main.rs.

main.rs: 3130 → 1586 lines (49% reduction).

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

poc-memory/src/cli/mod.rs

@@ -5,3 +5,5 @@
 
 pub mod graph;
 pub mod node;
+pub mod agent;
+pub mod admin;