docs: add literate prose to naming-drift aliases and HITL gateway changes

Adds prose sections before every code block to satisfy the
prose-before-code discipline. Each backward-compatibility alias
(process-signal, perceive-gate, reason-gate, act-gate, inject-stimulus)
now has its own subsection explaining why it exists and what new code
should use instead.

Also:
- Fixes double #+end_src in core-loop-perceive.org
- Renames inject-stimulus → stimulus-inject in heartbeat-start and
  client-handle-connection (both already had aliases)
- Adds HITL interception prose to gateway-manager.org telegram/signal
  sections
- Splits Pre-Reason Handler Registry into two code blocks (defvar + defun)
  for one-per-block compliance

org/core-loop-perceive.org

@@ -70,21 +70,34 @@ before the signal reaches the LLM. The handler receives the full signal
 and returns T if the signal was consumed (don't continue to reason)
 or nil if processing should proceed normally.
 
+*** Pre-Reason Handler Hash Table
+
 ;; REPL-VERIFIED: 2026-05-03T13:00:00
 #+begin_src lisp
 (defvar *pre-reason-handlers* (make-hash-table :test 'eq)
   "Pre-reason handler registry: sensor keyword → handler function.")
+#+end_src
 
+*** register-pre-reason-handler
+
+;; REPL-VERIFIED: 2026-05-03T13:00:00
+#+begin_src lisp
 (defun register-pre-reason-handler (sensor fn)
   "Registers FN to handle signals with SENSOR in the perceive gate.
 FN receives (signal) and returns T if consumed, nil to continue."
   (setf (gethash sensor *pre-reason-handlers*) fn))
-
-;; Alias for backward compatibility
-(defun inject-stimulus (raw-message &key stream (depth 0))
-  "Alias for stimulus-inject."
-  (stimulus-inject raw-message :stream stream :depth depth))
 #+end_src
+
+** inject-stimulus backward-compatibility alias
+
+Skills and external code that still call ~inject-stimulus~ (the previous
+name for the pipeline injection function) can use this alias. New code
+should call ~stimulus-inject~ directly.
+
+;; REPL-VERIFIED: 2026-05-03T13:00:00
+#+begin_src lisp
+(defun inject-stimulus (raw-message &key stream (depth 0))
+  (stimulus-inject raw-message :stream stream :depth depth))
 #+end_src
 
 ** Stimulus Injection (stimulus-inject)
@@ -139,12 +152,12 @@ The perceive gate is the first stage of the metabolic pipeline. It receives a no
 
 All signals get tagged with their processing stage (`:status :perceived`) and the current foveal focus before being passed to the Reason stage.
 
+*** loop-gate-perceive
+
+The main perceive pipeline stage.
+
 ;; REPL-VERIFIED: 2026-05-03T13:00:00
 #+begin_src lisp
-;; Alias: perceive-gate → loop-gate-perceive
-(defun perceive-gate (signal)
-  (loop-gate-perceive signal))
-
 (defun loop-gate-perceive (signal)
   "Stage 1 of the metabolic pipeline: Normalize sensory input."
   (let* ((payload (getf signal :payload))
@@ -199,6 +212,18 @@ All signals get tagged with their processing stage (`:status :perceived`) and th
     signal))
 #+end_src
 
+*** perceive-gate (backward-compatibility alias)
+
+The pipeline gate was originally named ~perceive-gate~. Code that still
+uses the old name can call this alias. New code should call
+~loop-gate-perceive~.
+
+;; REPL-VERIFIED: 2026-05-03T13:00:00
+#+begin_src lisp
+(defun perceive-gate (signal)
+  (loop-gate-perceive signal))
+#+end_src
+
 * Test Suite
 Verifies that the perceive gate correctly ingests AST nodes into memory and that the depth limiter prevents runaway recursive signals.
 #+begin_src lisp :tangle ../lisp/core-loop-perceive.lisp