fix(framework): ride the existing communicationStyle enum, drop the no-op USER.md edit (mos-dt review #960)

F1: defaults/USER.md is never installed (generated from templates/USER.md.template
via buildCommunicationPrefs). Editing it was a no-op asserting a phantom setting —
exactly the false-green §2 warns against. Reverted.
F2: the framework already has communicationStyle (direct|friendly|formal). §5 now
maps THOSE values to output instead of inventing technical|prose|brief (rule 9).
Minor: §6 states no mechanical prose check exists today; rule 1 points at §3.4.

Written-by: jarvis (dragon-lin)
Co-Authored-By: Claude Fable 5 <[email protected]>

packages/mosaic/framework/defaults/USER.md

@@ -26,18 +26,6 @@ It is loaded globally and applies regardless of runtime or project.
 - No sycophancy
 - Executive summaries and tables for overview
 
-### Comms style (agents read this to choose how they talk to you)
-
-Choose one. Agents match it for user-facing messages. The default is `technical`.
-This setting governs comms only. It does not change the documentation standard
-(`guides/WRITING-STYLE.md`), which is always MOS-STE.
-
-- **`technical`** (default) — MOS-STE structure: short, active, defined terms.
-- **`prose`** — full sentences and paragraphs, warmer register, fewer tables.
-- **`brief`** — status lines and bullet points, minimum words.
-
-> Comms style: technical
-
 ## Personal Boundaries
 
 (Add any personal boundaries or preferences agents should respect.)