feat(mem0-agent): read path, hooks, maintenance, CLI and skills

- pack.py: single-call context pack, budgeted, sanitized, cached, with
  served-id tracking that turns a citation into POSITIVE feedback
- assist.py: error-signature lookup (never raw stdout, which returned 0 results in v1)
- maintain.py: transactional consolidation (add merged -> verify -> delete sources)
- transcript.py: JSONL parsing into non-overlapping windows via a cursor
- cli.py: the twelve commands the hooks invoke; detached assist queues a block
  that the next prompt hook drains, keeping the hot path network-free
- hooks generated from one spec; plugin manifest, MCP wiring, five skills

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

integrations/mem0-agent/skills/stats/SKILL.md

@@ -0,0 +1,34 @@
+---
+name: stats
+description: Show what memory captured and retrieved, by type and over time, including what was dropped and why. Use when the user asks how many memories exist, what got stored this session, or whether memory is actually helping.
+---
+
+# Stats
+
+```bash
+mem0-agent stats             # this session plus the corpus for this project
+mem0-agent stats --session   # just this session's capture/injection activity
+```
+
+## What to look at
+
+**Session view** — how many turns were seen, hard-dropped, flagged, and written, plus which
+memories were served in the context pack and whether any were referenced. Dropped counts
+are grouped by reason, so "why didn't it save that?" has an actual answer.
+
+**Corpus view** — memories by type and age for the current `user_id` + `app_id`.
+
+## Reading the numbers
+
+- **A high drop rate is correct.** Most turns contain nothing durable. The previous version
+  wrote ~98 memories a day and the corpus became unusable; this one targets fewer than 15.
+- **Writes ≫ reads is the warning sign**, not a large drop count. If the corpus grows every
+  day but the pack is never referenced, the value isn't there — lower `capture` or
+  investigate what's being stored.
+- **A memory written minutes ago may not appear yet.** Extraction is asynchronous
+  (20s–5min). Don't report it as missing.
+- **`categories` being empty is expected** on anything less than a few hours old;
+  retrieval uses `metadata.type` instead.
+
+Summarize in prose — counts by type, what was captured this session, and whether the served
+memories were used. Only surface raw ids when the user is chasing a specific memory.