A1: S5F13-F18 exception recovery messages (E5 §9.5-9.7)

Catalog gains the recover-request / recover-complete / recover-abort
loop that closes E5's exception lifecycle.  Wire shapes:

  S5F13/F14  Exception Recover Request / Acknowledge
  S5F15/F16  Exception Recover Complete Notify / Acknowledge
  S5F17/F18  Exception Recover Abort Request / Acknowledge

Acks use the same AlarmAck byte already in use by S5F10/F12.  EXRESULT
on F15 is modelled as ASCII (the common case; vendor-specific richer
shapes are a YAML edit).

Round-trip tests cover all three pairs.  Server dispatch is left for a
later commit alongside the per-alarm AlarmStateMachine (Tranche C) —
this commit is wire-coverage only.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

data/messages.yaml

@@ -725,6 +725,70 @@ messages:
     builder: s5f12_exception_clear_confirm
     body: {kind: scalar, item_type: BINARY_BYTE, enum: AlarmAck, param: ack}
 
+  # S5F13 / S5F14 — Exception Recover Request / Acknowledge (E5 §9.5).
+  # Host asks the equipment to execute a specific recovery action from
+  # the EXRECVRA list that the prior S5F9 advertised.  EXRECVRA on F13
+  # is a single action string, distinct from the list of allowed actions
+  # on F9.  F14 echoes ACKC5 as our AlarmAck byte.
+  - id: S5F13
+    stream: 5
+    function: 13
+    w: true
+    builder: s5f13_exception_recover_request
+    parser: parse_s5f13
+    body:
+      kind: list
+      struct_name: ExceptionRecoverRequest
+      fields:
+        - {name: exid,     shape: {kind: scalar, item_type: U4}}
+        - {name: exrecvra, shape: {kind: scalar, item_type: ASCII}}
+
+  - id: S5F14
+    stream: 5
+    function: 14
+    builder: s5f14_exception_recover_ack
+    body: {kind: scalar, item_type: BINARY_BYTE, enum: AlarmAck, param: ack}
+
+  # S5F15 / S5F16 — Exception Recover Complete Notify / Acknowledge
+  # (E5 §9.6).  Equipment signals that the recovery action requested by
+  # the matching S5F13 has finished; EXRESULT carries any structured
+  # outcome the equipment wishes to report (we model it as ASCII, which
+  # is the common case — vendor-specific richer shapes are a YAML edit).
+  - id: S5F15
+    stream: 5
+    function: 15
+    w: true
+    builder: s5f15_exception_recover_complete_notify
+    parser: parse_s5f15
+    body:
+      kind: list
+      struct_name: ExceptionRecoverComplete
+      fields:
+        - {name: exid,     shape: {kind: scalar, item_type: U4}}
+        - {name: exresult, shape: {kind: scalar, item_type: ASCII}}
+
+  - id: S5F16
+    stream: 5
+    function: 16
+    builder: s5f16_exception_recover_complete_ack
+    body: {kind: scalar, item_type: BINARY_BYTE, enum: AlarmAck, param: ack}
+
+  # S5F17 / S5F18 — Exception Recover Abort Request / Acknowledge
+  # (E5 §9.7).  Host aborts a recovery action currently in flight.
+  - id: S5F17
+    stream: 5
+    function: 17
+    w: true
+    builder: s5f17_exception_recover_abort_request
+    parser: parse_s5f17
+    body: {kind: scalar, item_type: U4, param: exid}
+
+  - id: S5F18
+    stream: 5
+    function: 18
+    builder: s5f18_exception_recover_abort_ack
+    body: {kind: scalar, item_type: BINARY_BYTE, enum: AlarmAck, param: ack}
+
   # =====================================================================
   # S6 — Data collection
   # =====================================================================