feat(inception): the doors — create_project/decide_project_inception take the decision, enter_project asks until decided, REST inception endpoints, _INSTRUCTIONS (#2882, milestone 297 step 4)

- MCP create_project(..., exclude_always_on_rulebooks, subscribe_rulebooks,
  design_system_id (0 unstated / -1 none / n), seed_systems): any inception
  arg → inception.decide(via="mcp") after the create; none → undecided with
  an inception_hint. New decide_project_inception(project_id, …) records or
  re-records; nothing given = an inherit-all decision, stated.
- enter_project carries `inception` ONLY for the caller's own, undecided
  project: inception_ask() = the project's current defaults + what to ask the
  operator once + the exact call (the #2683 ask shape). Absent otherwise.
- REST: POST /api/projects accepts `inception` (validated before the create);
  POST /api/projects/<id>/inception decides/re-decides; GET …/inception/defaults
  is the card's payload; GET project already carries inception via to_dict.
- _INSTRUCTIONS: ORIENT names the ask; START a project names the questions —
  never create a project bare by default (product behaviour, P#119).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/mcp/server.py

@@ -37,7 +37,12 @@ in local files (CLAUDE.md, auto-memory); Scribe holds the single copy.
 
 Hierarchy: Project -> Milestone -> Task/Note. The map, by purpose:
 - ORIENT: enter_project(id) at session start — rules, open tasks, recent
-  notes, Systems and design system in one call.
+  notes, Systems and design system in one call. If it returns `inception`,
+  the project's inheritance was never decided: raise that ask once, then
+  decide_project_inception.
+- START a project: create_project takes what it inherits — always-on
+  rulebooks to exclude, rulebooks to subscribe, design system, seed
+  Systems. Ask the operator first; never create a project bare by default.
 - DO: create_task. Fixed a problem? kind="issue" (symptom -> root cause ->
   fix), never a work-log line on an unrelated task. Log with add_task_log;
   keep status honest — in_progress on start, done on finish.