Phase 3: JEV classification, rules table, editable categories (AUD-69)

Implements FR-3, FR-4, FR-5 and FR-14.

- internal/classify: TypeSafe System One (JEV) HTTP client with the confirmed
  request/response shape, retry with backoff on 429/529/5xx, a plain-text rule
  engine (first match wins, overrides only the named fields), and bounded
  orchestration with a per-run cap.
- internal/store: migration v3 adds an editable `categories` table (name =
  JEV Choice option and classifications key; rename cascades, remove reassigns)
  and seeds a starter rules version once. Classification persistence, coverage,
  and pending/all message queries.
- internal/server: POST /actions/classify and /actions/reclassify, plus the
  FR-14 category editor (GET /categories and add/rename/remove). The triage list
  now groups by the live category list and shows action + confidence.
- CLI: -classify and -classify-all for n8n.
- Docs: docs/phase3-classify.md with the confirmed JEV shape, a live read-only
  classification, and the DoD evidence.

DoD: all 100 stored messages have a non-null category, importance, and suggested
action (0 nulls); JEV picked a newly added/renamed category for 6 real messages
over HTTP. One live JEV call recorded in the phase doc.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.env.example

@@ -31,8 +31,14 @@ EMAIL_AGENT_IMAP_LOOKBACK_DAYS=14
 EMAIL_AGENT_IMAP_MAX_MESSAGES=100
 
 # --- Integrations (used from later phases) ---------------------------------
+# JEV is the TypeSafe System One HTTP API. JEV_BASE_URL defaults to the
+# documented host https://api.typesafe.ai when unset.
 JEV_BASE_URL=
 JEV_API_KEY=
+JEV_MODEL=jev-latest
+# Classifier bounds (FR-3): in-flight JEV requests, and messages per run.
+EMAIL_AGENT_CLASSIFY_CONCURRENCY=4
+EMAIL_AGENT_CLASSIFY_MAX_MESSAGES=200
 OMNIROUTE_BASE_URL=
 OMNIROUTE_API_KEY=
 HUB_TOKEN=