Bootstrap Level 19 structure and initialization

PR: BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP

Author: DavidQ

docs/dev/CODEX_COMMANDS.md

@@ -1,3 +1,3 @@
 MODEL: GPT-5.3-codex
 REASONING: high
-COMMAND: Prepare Level 19 planning structure and package to <project folder>/tmp/PLAN_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.zip
+COMMAND: Initialize Level 19 structure and package to <project folder>/tmp/BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.zip

docs/dev/COMMIT_COMMENT.txt

@@ -1 +1,3 @@
-Initialize Level 19 planning bootstrap
+Bootstrap Level 19 structure and initialization
+
+PR: BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP

docs/dev/reports/validation_checklist.txt

@@ -1,2 +1 @@
-- [ ] plan created
-- [ ] no unintended changes
+- [ ] structure created

docs/pr/BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.md

@@ -0,0 +1,37 @@
+# BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP
+
+## Purpose
+Execute a docs-only bootstrap for Level 19 so follow-on PRs can proceed in small, singular, roadmap-aligned slices.
+
+## Source of Truth
+- `docs/pr/PLAN_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.md`
+- `docs/dev/roadmaps/MASTER_ROADMAP_HIGH_LEVEL.md` (`## 18. Finalize engine`)
+- `docs/dev/roadmaps/phases.txt`
+
+## Exact Build Target
+Create and finalize Level 19 bootstrap planning structure docs only. No code/runtime implementation is allowed in this PR.
+
+## Required Outputs
+- finalized `docs/pr/PLAN_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.md`
+- finalized `docs/pr/BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.md`
+
+## Functional Requirements
+1. BUILD scope must remain planning/bootstrap only.
+2. BUILD must map to Section 18 continuity and the existing no-Phase-19+ roadmap note.
+3. BUILD must define this PR as initialization-only (no feature implementation).
+4. Packaging must include only files changed for this bootstrap PR.
+
+## Non-Goals
+- no `src/` changes
+- no `samples/`, `games/`, or `tools/` implementation changes
+- no test logic changes
+- no roadmap checkbox status updates
+
+## Validation
+- verify source docs exist and are readable
+- verify required output docs exist
+- confirm no implementation files were modified by this PR scope
+
+## Packaging Rule
+Package only this PR's created/modified files into:
+`tmp/BUILD_PR_LEVEL_19_1_NEXT_PHASE_BOOTSTRAP.zip`