docs: drop the stale hard-cap-4-workers prompt description

CL-7001 is removing the same claim from the actual prompt text
(src/agent/prompts.ts, skywalker/package.ts) since no concurrency cap
exists in code. Removing it here too so the two land consistent.

Author: TheGreatAxios

docs/ARCHITECTURE.md

@@ -295,7 +295,7 @@ Data-only agent plugins (`src/plugins/data-only-agent.ts`) synthesize `agentPlug
 
 ### System Prompt (`src/agent/prompts.ts`)
 
-The primary session identity is **Skywalker** (`buildChatRole` → `createSkywalkerSystemPrompt`). Product name remains Corbits Code; when asked its name, the primary answers Skywalker. Role: orchestrate — classify, DIY tiny/single-file/one-route product edits, dispatch closed directors via `task` for substantial work, track the fleet, synthesize. Product mutation tools (`write_file` / `edit_file` / `delete_file`) are mounted on the primary session (CORE and `SKYWALKER_TOOLS`) so Skywalker can DIY bounded edits; spawn remains the default for substantial, multi-file, parallel, or specialist work (hard cap 4 workers). Shell file-writes stay denied by auto-shell policy. MCP tools are not re-filtered by a product-write deny list (that list is gone). There is no static per-leaf write-path lock; concurrent lanes sharing a cwd are instead flagged (not blocked) as a `conflict` intervention. A frontier model already knows how to code; the static prompt carries harness-specific facts and the closed-fleet orchestration policy. The base is three individually-exported sections:
+The primary session identity is **Skywalker** (`buildChatRole` → `createSkywalkerSystemPrompt`). Product name remains Corbits Code; when asked its name, the primary answers Skywalker. Role: orchestrate — classify, DIY tiny/single-file/one-route product edits, dispatch closed directors via `task` for substantial work, track the fleet, synthesize. Product mutation tools (`write_file` / `edit_file` / `delete_file`) are mounted on the primary session (CORE and `SKYWALKER_TOOLS`) so Skywalker can DIY bounded edits; spawn remains the default for substantial, multi-file, parallel, or specialist work. Shell file-writes stay denied by auto-shell policy. MCP tools are not re-filtered by a product-write deny list (that list is gone). There is no static per-leaf write-path lock; concurrent lanes sharing a cwd are instead flagged (not blocked) as a `conflict` intervention. A frontier model already knows how to code; the static prompt carries harness-specific facts and the closed-fleet orchestration policy. The base is three individually-exported sections:
 
 - `buildChatRole` — Skywalker primary identity (orchestrate; DIY tiny/bounded product edits; spawn for substantial work).
 - `buildHarnessFacts` — the non-derivable rules: shell file-writes are blocked, path tools are the DIY surface on primary (spawn build/docs directors for substantial work), dependency installs and off-limits paths need approval, images are native multimodal input, only core tools are resident (load the rest via `tool_search`; use `search_agents` before dispatching specialists), workflows run only from slash-command steps, and session memory lives at `.corbits/MEMORY.md`.