emrg: remove pre-wrap from .msg.user (fix trailing blank line in user bubbles)

[argszero]

Fixes the GUI issue where sent user messages render with an extra blank line at the bottom of the bubble.

Root cause (verified):

• .msg.user CSS kept white-space: pre-wrap from the vanilla plain-text bubble era (gui/renderer/css/components.css:63)
• User messages are markdown-rendered (Stage 1, rant 2026-08-28T14:07:29): marked.parse always ends output with a bare \n → the text node after the closing
  renders as a visible line break under pre-wrap
• Assistant messages are unaffected (.msg-body has no pre-wrap); history user messages inherit .msg.user and were equally affected

Fix (minimal):

• Remove white-space: pre-wrap from .msg.user, keep word-break: break-word — one rule fixes both live and history user bubbles
• Paragraph spacing is handled by block-level

  structure, so no layout regression

• Shift+Enter hard breaks stay covered by markdown paragraphization (out of scope here per rant)

Verification: renderer typecheck clean, full suite 499 passed (45 files).

[argszero]

✅ LGTM — cycle cyc20260902-141353

Reviewed the CSS fix (diff against master 9e4dffe):

• Root cause is correctly identified and the fix is minimal: removing vanilla-era white-space: pre-wrap from .msg.user (marked.parse output ends with a bare \n → the text node after
  renders as a visible blank line under pre-wrap).
• word-break: break-word retained — no layout regression; paragraph spacing is handled by block-level

  structure.

• One rule fixes both live (.msg.user) and history (.msg.user.history) bubbles since the latter inherits.
• Other pre-wrap uses (tool-result, memory-detail, toast) are legitimate plain-text blocks — correctly untouched.
• Renderer typecheck clean + full suite 499 passed (45 files); CI test + test-windows green (33597514301).

[argszero]

✅ LGTM — cycle cyc20260902-142103

Second consecutive approval (1/3 cyc141353 → this cycle 2/3). Head 560bfea unchanged, CI test + test-windows green (33597514301), CLEAN. Fix re-verified on this exact head: .msg.user pre-wrap removal is the minimal correct change (trailing \n text node no longer renders as a blank line); word-break retained; live + history bubbles both covered.

[argszero]

✅ LGTM — cycle cyc20260902-142801

Third consecutive approval (1/3 cyc141353, 2/3 cyc142103, this cycle 3/3). Head 560bfea unchanged, CI test + test-windows green (33597514301), CLEAN. No ❌ in between. Merging.