feat: unified streaming infrastructure (draft — awaiting streaming impl)

Unified streaming architecture combining the best of PRs #774 and #798,
with improvements. This is a draft — awaiting proper streaming token
implementation and testing before merge.

Layer 1 — Core streaming (run_agent.py):
- stream_delta_callback on AIAgent.__init__ (per-instance)
- _interruptible_streaming_api_call() for chat completions with
  SimpleNamespace response reconstruction
- Tool-call suppression (callback only fires for text-only responses)
- on_first_delta callback (stops thinking spinner on first token)
- Provider fallback when streaming unsupported
- reasoning_content accumulation
- Interrupt support (client.close() + rebuild)

Layer 2 — Display (cli.py, gateway/):
- CLI: line-buffered _stream_delta/_flush_stream via _cprint
- Gateway: async stream consumer with dual transport:
  * Draft (Bot API 9.3+ sendMessageDraft) as primary
  * Progressive editMessageText as fallback
  * Auto mode tries draft, falls back seamlessly
- Config-driven: streaming.enabled, edit_interval, buffer_threshold,
  cursor, transport (auto/draft/edit)
- Uses self.config (no duplicate yaml reads)
- already_sent flag prevents duplicate sends in base.py

Telegram-specific (gateway/platforms/telegram.py):
- send_raw / edit_message_raw (plain text, no MarkdownV2)
- send_draft / finalize_draft (Bot API 9.3+)
- delete_message
- All methods pass message_thread_id for forum topic support
  (fix for #774's missing thread_id bug)

Tests: 10 new tests covering accumulator shape, callback order,
tool-call suppression, provider fallback, already_sent contract.

Config example:
  streaming:
    enabled: true
    edit_interval: 1.0
    buffer_threshold: 100
    cursor: ' ▉'
    transport: auto  # auto, draft, or edit

Supersedes: #774 (jobless0x), #798 (OutThisLife), #697 (clicksingh)

cli.py

@@ -1253,6 +1253,7 @@ class HermesCLI:
         # Background task tracking: {task_id: threading.Thread}
         self._background_tasks: Dict[str, threading.Thread] = {}
         self._background_task_counter = 0
+        self._stream_buf = ""
 
     def _invalidate(self, min_interval: float = 0.25) -> None:
         """Throttled UI repaint — prevents terminal blinking on slow/SSH connections."""
@@ -1495,6 +1496,7 @@ class HermesCLI:
                 platform="cli",
                 session_db=self._session_db,
                 clarify_callback=self._clarify_callback,
+                stream_delta_callback=self._stream_delta,
                 honcho_session_key=self.session_id,
                 fallback_model=self._fallback_model,
                 thinking_callback=self._on_thinking,
@@ -3339,6 +3341,28 @@ class HermesCLI:
             "Use your best judgement to make the choice and proceed."
         )
 
+    _stream_started = False
+
+    def _stream_delta(self, text: str):
+        """Buffer streaming tokens; emit complete lines via _cprint."""
+        if not text:
+            return
+        if not self._stream_started:
+            text = text.lstrip("\n")
+            if not text:
+                return
+            self._stream_started = True
+        self._stream_buf += text
+        while "\n" in self._stream_buf:
+            line, self._stream_buf = self._stream_buf.split("\n", 1)
+            _cprint(line)
+
+    def _flush_stream(self):
+        """Emit any remaining partial line from the stream buffer."""
+        if self._stream_buf:
+            _cprint(self._stream_buf)
+        self._stream_buf = ""
+
     def _sudo_password_callback(self) -> str:
         """
         Prompt for sudo password through the prompt_toolkit UI.
@@ -3467,6 +3491,8 @@ class HermesCLI:
 
         # Add user message to history
         self.conversation_history.append({"role": "user", "content": message})
+        self._stream_buf = ""
+        self._stream_started = False
         
         _cprint(f"{_GOLD}{'─' * 40}{_RST}")
         print(flush=True)
@@ -3514,6 +3540,7 @@ class HermesCLI:
                     agent_thread.join(0.1)
             
             agent_thread.join()  # Ensure agent thread completes
+            self._flush_stream()
 
             # Drain any remaining agent output still in the StdoutProxy
             # buffer so tool/status lines render ABOVE our response box.
@@ -3542,7 +3569,7 @@ class HermesCLI:
                 if response and pending_message:
                     response = response + "\n\n---\n_[Interrupted - processing new message]_"
             
-            if response:
+            if response and not (self.agent and self.agent.stream_delta_callback):
                 # Use a Rich Panel for the response box — adapts to terminal
                 # width at render time instead of hard-coding border length.
                 try: