TASK-046: housekeeping — mark Done, simplify gates, persist review notes

Apply validation-loop polish from the review pass:
- Extract a hooks_armed lambda in connection_notify to deduplicate the
  any_hooks_ relaxed-load + cast spelled out at each call site.
- Collapse the three structurally-identical fire_* helpers in
  hook_handle.cpp onto a single fire_hooks_for_phase template, so the
  snapshot-lock-iterate-catch pattern lives in one place ahead of
  TASK-047..051 which would otherwise replicate it eight more times.

Mark TASK-046 Done in the task index and persist the unworked review
findings (24 minor, 0 major/critical) for later sweep.

Author: etr

specs/tasks/_index.md

@@ -128,7 +128,7 @@ Nominally: **13 sequential tasks**, each S–XL. Most other tasks parallelize of
 | TASK-035 | Smart-pointer `register_ws_resource` overloads | M5 | Done | TASK-014, TASK-034 |
 | TASK-036 | Handler return-by-value dispatch cutover | M5 | Done | TASK-022, TASK-025, TASK-027, TASK-031 |
 | TASK-045 | Hook bus skeleton (`hook_phase`, `hook_action`, `hook_handle`, `webserver::add_hook`) | M5 | Done | TASK-009, TASK-014 |
-| TASK-046 | Fire `connection_opened` / `connection_closed` / `accept_decision` | M5 | Not Started | TASK-045 |
+| TASK-046 | Fire `connection_opened` / `connection_closed` / `accept_decision` | M5 | Done | TASK-045 |
 | TASK-047 | Fire `request_received` and `body_chunk` (pre-handler short-circuit) | M5 | Not Started | TASK-045 |
 | TASK-048 | Fire `route_resolved` and `before_handler`; wire 404/405/auth aliases | M5 | Not Started | TASK-045, TASK-027, TASK-031 |
 | TASK-049 | Fire `handler_exception`; wire `internal_error_handler` alias | M5 | Not Started | TASK-045, TASK-031 |