docs: add P15-A and P15-B specs and plans, register both in ROADMAP

Two batches, one per repo, so they can run in parallel under the one-writer-per-repo
rule: P15-A refactors crearte-server's Approve function, P15-B fixes a dark-mode gap
in crearte's game loading screen plus two guard items.

P15-A splits a 169-line function whose seven phases are mapped here with real line
numbers — the base-tree mapping logged during P14 is void, since that batch moved the
function into moderation.go. The spec's central constraint is that phases four and six
look alike but must not be merged: four is an optimistic pre-check that runs unlocked
before any object copy, six is a pessimistic re-check under a row lock after the copies
have happened. They differ in four concrete ways (kind coverage, the NewVersion runtime
and bundle checks, whether entities are created, and the error wrapping), so the
apparent duplication is deliberate TOCTOU defence rather than removable redundancy.
A measurement also overturned the survey's claim about helper shape: both an unexported
method and a package-level function leave all seven P14 assertions green, because
IsExported filtering and NumMethod's exported-only view put neither in scope. The
choice is therefore about needing receiver fields, not about the guard.

P15-B fixes a gap P13 left: its token work covered only the src/index.html entry and
missed the second Vite entry, bootstrap, so the game loading screen hardcodes light
values and dark-theme users see a white flash on every virtual game launch. The fix
rides the hash channel bootstrap already parses rather than inventing a postMessage
protocol, which would be async and so repaint light first — the very flash being
removed. The spec records the trap that makes this easy to get wrong: GameHost builds
targets in a computed, so injecting the reactive theme ref would make a theme switch
recompute the iframe src and reload a game in progress; the non-reactive snapshot is
required, and a guard leg plus a mutation exist solely to hold that line. It also
records two pre-existing contrast violations found on the way, where inline style
attributes override conforming stylesheet values with lower-contrast ones, and why
noHardcodedColor cannot be extended to cover this file: it only collects .vue and
blanks out style blocks, so widening its roots would scan nothing while looking
like coverage.

Every line number and quoted signature in both specs was checked against source
before commit; two claims the survey had asserted from reasoning were measured
instead, and one of them was wrong.

docs/ROADMAP.md

@@ -74,3 +74,5 @@
 | P12 窄屏溢出修复与打磨批 | `docs/specs/2026-10-02-p12-narrow-viewport-overflow-design.md` | `docs/plans/2026-10-02-p12-narrow-viewport-overflow.md`（已执行，2026-10-02：crearte 0.25.0 / server 0.17.1 / deploy 0.7.1） |
 | P13 暗色模式 | `docs/specs/2026-10-03-p13-dark-mode-design.md` | `docs/plans/2026-10-03-p13-dark-mode.md`（已执行，2026-10-03：crearte 0.26.0） |
 | P14 拆分 ContentService god object | `docs/specs/2026-10-03-p14-content-service-split-design.md` | `docs/plans/2026-10-03-p14-content-service-split.md`（已执行，2026-10-03：crearte-server `fe810dd` 0.18.0） |
+| P15-A 拆分 Approve 七阶段 | `docs/specs/2026-10-03-p15a-approve-phases-design.md` | `docs/plans/2026-10-03-p15a-approve-phases.md`（进行中，2026-10-03：crearte-server） |
+| P15-B bootstrap 暗色 + 守卫补钉 + 死令牌清理 | `docs/specs/2026-10-03-p15b-bootstrap-dark-design.md` | `docs/plans/2026-10-03-p15b-bootstrap-dark.md`（进行中，2026-10-03：crearte） |