feat: spawn_agent tool + host max_concurrent + docs

Adds a synchronous sub-agent spawning tool that lets the orchestrator
delegate tasks to a specific role's model and tool set.

- cortex/tools/agents.py: spawn_agent(task, role, tier, timeout, max_rounds)
  - Supports local_openai and gemini_api model types
  - Per-host asyncio semaphore (keyed by host_id or model type)
  - asyncio.wait_for() enforces timeout; admin-only tool
- cortex/model_registry.py: max_concurrent field in host schema (default 3,
  clamped 1-20); backfilled on _normalize() for existing hosts
- cortex/routers/local_llm.py + local_llm.html: "Max parallel" number input
  in host add/edit forms
- cortex/tools/__init__.py: spawn_agent registered in TOOL_CATEGORIES["Agents"],
  _CALLABLES, TOOL_ROLES (admin), and _ALL_DECLARATIONS
- Docs: TOOLS.md count 44→45, spawn_agent section; HELP.md tool table updated;
  ARCH__FUTURE.md Round 2 completed items; TODO__Agents.md spawn_agent checked;
  CLAUDE.md tool count and list updated

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/static/HELP.md

@@ -82,12 +82,12 @@ Orchestrated sessions persist to history exactly like regular chat.
 
 ### Available Tools
 
-40 tools across 11 categories. Each tool schema is sent to the model on every orchestrated call — fewer active tools means fewer tokens per call.
+45 tools across 12 categories. Each tool schema is sent to the model on every orchestrated call — fewer active tools means fewer tokens per call.
 
 | Category | Tools |
 |---|---|
 | **Web** | `web_search`, `http_fetch` |
-| **Files** | `file_read`, `file_list`, `file_write` |
+| **Files** | `file_read`, `file_list`, `file_write`, `session_search` |
 | **Shell** | `shell_exec`, `claude_allow_dir` |
 | **System** | `cortex_restart`, `cortex_logs`, `cortex_status`, `cortex_update` |
 | **Tasks** | `task_list`, `task_create`, `task_update`, `task_complete` |
@@ -97,8 +97,9 @@ Orchestrated sessions persist to history exactly like regular chat.
 | **Notifications** | `web_push`, `email_send`, `nc_talk_send` |
 | **Aether Journals** | `ae_journal_list/search`, `ae_journal_entries_list`, `ae_journal_entry_read/create/update/disable/append/prepend` |
 | **Agent Notes** | `agent_notes_read`, `agent_notes_write`, `agent_notes_append`, `agent_notes_clear` |
+| **Agents** | `spawn_agent` |
 
-File, Shell, System, and some Notification tools are **admin-only** and not visible to regular users.
+File, Shell, System, Agents, and some Notification tools are **admin-only** and not visible to regular users.
 
 ### Per-Role Tool Sets
 
@@ -277,6 +278,8 @@ Leave all slots empty to use the server default.
 
 **Per-role tool sets:** Expand any role card to configure which tool categories the orchestrator can use when that role is active. Unchecked categories are hidden from the model entirely — reducing token overhead on every orchestrated call. Leaving all categories unchecked means all tools the user has access to are available (the default).
 
+**Inject timestamp:** Each role card has an "Inject current date & time into system prompt" checkbox (default on). Disable it for pure processing roles (summarizer, classifier, translator) that don't need clock awareness.
+
 ---
 
 ## Nextcloud Talk Bot

cortex/static/TOOLS.md

@@ -1,6 +1,6 @@
 # Tool Reference
 
-> This reference covers all 44 orchestrator tools available when the ⚡ toggle is on.
+> This reference covers all 45 orchestrator tools available when the ⚡ toggle is on.
 > Tools are invoked automatically by the orchestrator — you don't call them directly.
 
 ¹ **Admin only** — requires the `admin` role. Invisible to regular users.  
@@ -113,3 +113,11 @@ Private, durable notes visible only to the orchestrator — not surfaced to user
 | `agent_notes_write` | Overwrite the notes file completely |
 | `agent_notes_append` | Append a timestamped entry (keeps last 3 backups automatically) |
 | `agent_notes_clear` | Erase all notes (backs up first) |
+
+## Agents ¹
+
+Spawn sub-agents that run their own tool loop using a specific role's model and tools.
+
+| Tool | What it does |
+|---|---|
+| `spawn_agent` ¹ | Spawn a sub-agent synchronously — blocks until the task completes or times out. Params: `task`, `role` (default `chat`), `tier` (1–4, default 1), `timeout` seconds, `max_rounds` override. Only works with `local_openai` and `gemini_api` models. |

cortex/static/local_llm.html

@@ -403,6 +403,10 @@
                   <option value="openai">OpenAI-compatible (OpenRouter, etc.)</option>
                 </select>
               </div>
+              <div class="field" style="flex:0 0 auto; width:6rem">
+                <label>Max parallel</label>
+                <input type="number" name="max_concurrent" min="1" max="20" value="3" style="width:100%">
+              </div>
             </div>
             <div class="btn-row">
               <button type="submit" class="btn btn-primary btn-sm">Add Host</button>