docs: land prior ADR + prompt updates

Commit pre-existing uncommitted working-tree changes that predate the
license/public-readiness work — NOT authored in this session, just flushed so
they're not lost: ADR-0003/0005/0009/0012 edits, the new ADR-0013
(embeddings-bypass + two-slot residency, already referenced by CLAUDE.md), and
the phase-0..3 prompt revisions + prompts/README.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/adr/0003-api-surface.md

@@ -40,8 +40,8 @@ only if a non-go-llm caller needs it.
 - "Set up the Mac as a go-llm target" needs zero provider changes — a thin
   constructor only (ADR-0011).
 - Preserves `think:false`, reliable tool calls, and lower latency.
-- foreman must faithfully proxy native `/api/chat` semantics, including SSE
-  streaming (ADR-0012).
+- foreman must faithfully proxy native `/api/chat` semantics, including NDJSON
+  streaming (`application/x-ndjson`, not SSE; ADR-0012).
 
 ## Alternatives considered