feat(410): the Claude Code plugin becomes a thin adapter (#4031)

Step 4 of milestone 410 "One owner per piece of guidance". The plugin's
static session context was a second copy of using-scribe and the server
index. It now says only what Claude Code needs said: 8,705 -> 1,791 chars.

scribe_static_context.md:
- points at using-scribe for how to work with Scribe, and names the process
  skills
- Claude Code specifics: keep one copy in Scribe rather than CLAUDE.md or
  auto-memory (leave auto-memory at its default); injected lines are
  retrieval, not the whole set; compact at clean seams; stored Processes
  arrive as scribe-proc-* skills with /scribe:sync; say so when the tools
  are unavailable
- retired: the restated reflexes, "how the surfaces divide the work", and
  the "follow the surface that assumes least" precedence (decision #4027)

Hook behaviour is unchanged. The SessionStart hook header says what the
static tier now carries, and the unreachable-instance status points at the
using-scribe skill instead of "the standing guidance above".

README and manifest describe the plugin as the Claude Code adapter over the
shared, client-neutral skills. Fixed along the way: the README said the
SessionStart hook "injects your rules" and suggested disabling auto-memory,
both contradicting the product since milestone 394.

Tests: the session-start rules guards now pin the owner (using-scribe) and
the index (_INSTRUCTIONS) rather than every surface; the Systems-reflex and
snippet-trigger guards pin their owners; the reporting-reflex guard pins
using-scribe. The loss guard and client-neutral guard stay green. Plugin
version minted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
-  "description": "Scribe system-of-record for Claude Code: MCP tools over your notes/tasks/projects/rules, a session-start push channel that surfaces your active-project context, process-skills (writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code), and your saved Scribe Processes auto-surfaced as skills (/scribe:sync). Replaces superpowers + file-memory with one app-backed plugin.",
-  "version": "2026.09.14.1550",
+  "description": "Scribe for Claude Code: connects the scribe MCP server, adds the hooks that deliver live project state and relevant records at the right moment, ships the shared client-neutral Scribe skills (using-scribe, writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code, shape-accounting), and syncs your saved Scribe Processes as skills (/scribe:sync).",
+  "version": "2026.09.14.1645",
   "author": {
     "name": "Bryan Van Deusen"
   },