fix(linkedin-studio): S4 harden multiplatform — Step-0 empty-source fallback + cross-platform buzzword line

S4 close-out (2 edits / 1 command file · lint 81/0 · counts 29/19/26/6):
- multiplatform.md:28 Step 0: empty-source fallback (drafts empty + no recent posts + nothing pasted -> stop, ask user to paste; never fabricate source)
- multiplatform.md:45 Adaptation Templates: cross-platform voice-hygiene line (banned buzzwords = content rule #4; adaptation rewrites can introduce them)

Class call: NOT post-emitting (output is Twitter/slides/YouTube) -> no LinkedIn predicate imposed; tested as guided/cross-format + routing sub-predicate. Routing (/linkedin:newsletter) + both reference files resolve; no subagents. Axis-c (buzzword) + axis-d (degradation) closed; axes a/b PASS. Local-only per push policy.

commands/multiplatform.md

@@ -24,6 +24,10 @@ Ask the user to provide their LinkedIn content or read from drafts:
 - Read `${LINKEDIN_STUDIO_DATA:-$HOME/.claude/linkedin-studio}/drafts/` for recent content
 - Read `~/.claude/linkedin-studio.local.md` for recent posts
 
+If none of these yields source content (empty/absent drafts, no recent posts, and nothing
+pasted), **stop and ask the user to paste the LinkedIn post to adapt** — never fabricate
+source content to adapt.
+
 ## Step 1: Select Target Platform
 
 > **Long-form lives elsewhere.** Newsletters, blog posts, and essays are produced by
@@ -38,6 +42,11 @@ Use AskUserQuestion:
 
 ## Adaptation Templates
 
+> **Voice hygiene (all platforms):** adaptation rewrites the source — keep the adapted copy free
+> of the banned corporate buzzwords (content rule #4: leverage, synergy, paradigm shift, thought
+> leader, disruptive, value proposition, ecosystem, holistic approach) on every platform; don't
+> let the rewrite introduce them.
+
 ### LinkedIn → Twitter/X Thread
 
 ```