feat(plugin): Scribe replaces native memory by instruction; tighten project-scope discipline

Direction change (operator, see plan task #755 work-log): the plugin must
NOT depend on disabling a native Claude function to work. It earns its place
by steering behavior, not by toggling autoMemoryEnabled.

Memory doctrine (no dual-write):
- using-scribe SKILL.md gains "Scribe holds these functions — don't keep a
  second copy": route rules/recall/planning to Scribe, don't also write them
  to native auto-memory, never instruct disabling a native function, and
  accept a "Scribe-shaped hole" if the plugin is removed (recover over time).
- mcp/server.py _INSTRUCTIONS: drop the paragraph that told the model to
  create/refresh a "rules live in Scribe" pointer in CLAUDE.md / ~/.claude
  memory. That was an active dual-write instruction; the SessionStart hook is
  the bridge now. Replaced with the no-dual-write / no-settings-dependency
  doctrine. Supersedes plan #755 Phase 6 ("set autoMemoryEnabled:false").

Project-scope discipline (stop cross-project bleed):
- using-scribe SKILL.md gains "Stay inside the active project's scope": pass
  project_id to every read, only reference/offer work on the in-scope project,
  ask before switching.
- _INSTRUCTIONS scope bullet extended from reads to referencing/offering, and
  flags get_recent as cross-project.
- get_recent docstring gains a scope note steering to scoped list_* when a
  project is active.

plugin.json 0.1.4 -> 0.1.5 so clients' caches actually refresh (re-shipping
under the same version does not bust the cache).

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

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe second brain for Claude Code: MCP tools over your notes/tasks/projects/rules, a session-start push channel that surfaces your always-on rules + active-project context, and a set of universal process-skills (brainstorm, debug, TDD, plan, verify). Replaces superpowers + file-memory with one app-backed plugin.",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "author": { "name": "Bryan Van Deusen" },
   "mcpServers": {
     "scribe": {