host P1: types DECLARE behavior, runner DERIVED (LIVE-VERIFIED)

Generalizes the hardcoded publish trigger into declared, capability-routed behavior.

- Types carry :behavior — flat string-keyed bindings {"verb" "type" "dag"} on the type-post
  (persist-safe, like :type-relations). The "article" type declares on-create → the "publish" DAG.
- host/blog--load-behaviors! gathers ALL posts' declarations into a registry at boot (serve.sh); the
  trigger match (host/blog--triggers :match = host/blog--match-behaviors) consults it. Hardcoded
  create+article trigger removed.
- Runner DERIVED (DEBT #2 fixed): match resolves :dag via host/blog--dag-registry and picks the
  runner via host/flow--select-runner over host/blog--runner-fleet ([exec-runner]; RA joins at
  RA-live). Each binding carries its :runner; behavior/-run-binding now uses the binding's runner
  (else the engine default) — so the capability model drives the LIVE engine.
- The type-def view shows each behavior + its derived runner (host/blog--behavior-lines).

LIVE PROOF: /article shows 'on create → publish DAG · needs {effect, branch} · runner: synchronous
(exec-fold)'; publishing on blog.rose-ash.com fired /flows validate+notify via the DECLARED path.
blog 213/213 (+3 P1), full host conformance 610/610. FINDING: load-behaviors! scans all posts, not
is-type?-filtered (article failed is-type? on the durable store though it passed in-memory).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/host/tests/blog.sx

@@ -175,6 +175,17 @@
 ;; the relation metadata into the in-memory cache the same way.
 (host/blog-seed-types!)
 (host/blog-load-rel-kinds!)
+(host/blog--load-behaviors!)   ;; P1: gather types' declared behaviors into the registry (as boot does)
+(host-bl-test "P1: load-behaviors! gathers the article type's declared on-publish binding"
+  (list (>= (len host/blog--behaviors) 1)
+        (contains? (map (fn (b) (get b "dag")) host/blog--behaviors) "publish"))
+  (list true true))
+(host-bl-test "P1: match-behaviors resolves a create/article activity → a binding with a DERIVED runner"
+  (let ((ms (host/blog--match-behaviors {:verb "create" :object-type "article"})))
+    (list (len ms) (get (get (first ms) :runner) :capabilities)))
+  (list 1 (list "effect" "branch" "each")))
+(host-bl-test "P1: a non-article activity matches nothing"
+  (len (host/blog--match-behaviors {:verb "create" :object-type "note"})) 0)
 (host-bl-test "relate no auth -> redirect to login"
   (dream-status (host-bl-wapp (host-bl-send "POST" "/my-first-post/relate" nil
     "application/x-www-form-urlencoded" "other=another-one"))) 303)