feat(i18n): new documents merge bilingual — the requiredSince date frontier

New docs must not enlarge the translation backlog: any date-named
document (yyyy-mm-dd-*.md, i.e. an RFC) dated on/after the manifest's
requiredSince cutoff must merge with its complete pair, independent of
the required back-catalog list. Cutoff ships at 2026-07-05, so the
existing 2026-07-04 RFC wave is grandfathered into the batch backlog
and everything after is bilingual from birth.

The date comes from the filename, deliberately: it is deterministic
from tree content alone — no git history (shallow CI checkouts hold),
no PR base ref — matching the gate's pure-content design. A proposal
dated before the cutoff that merges later escapes the rule; that is
the graceful grandfathering of in-flight work, not a hole.

--list marks such files (required by date); contract and RFC updated
in both languages and the pairs re-recorded.

docs/rfc/implemented/process/2026-07-02-bilingual-docs-and-pairing-gate.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write
-2026-07-02-bilingual-docs-and-pairing-gate.md: 517a6371eca5d747313c7efdb2756a50257701e4
-2026-07-02-bilingual-docs-and-pairing-gate.zh.md: f8f68bf5d4d7e6795318d9dd435a525f20a4f407
+2026-07-02-bilingual-docs-and-pairing-gate.md: 764ad5a9345c2a138b56e9cedb54848a5f7d6054
+2026-07-02-bilingual-docs-and-pairing-gate.zh.md: f039fbe3fa44cb379905bbea9a4692af19d71230

docs/rfc/implemented/process/2026-07-02-bilingual-docs-and-pairing-gate.md

@@ -32,5 +32,5 @@ Paired sibling files with locale suffixes are the dominant Chinese big-tech conv
 - Every pair adds a third file to the tree. The record is machine-written (`--write`), so the cost is directory noise, not maintenance effort; in exchange, "who confirmed these consistent, and when" is answerable from git blame on the yaml.
 - When the two sides disagree, no mechanical rule picks a winner — the PR review does. That is the price of equal authority, accepted deliberately: the alternative (a canonical language) forbids Chinese-first authoring.
 - Generated docs (`cordis-catalog/`, `tool-catalog/`, `module-graph.md`) are excluded for now; the planned follow-up is to teach their generators to emit Chinese alongside English, at which point they leave the exclusion list.
-- Rollout is incremental by design: documents outside `required` are visible backlog (`--list`), not red CI, so pairs land in reviewable batches without a big-bang PR.
+- Rollout is incremental by design: documents outside `required` are visible backlog (`--list`), not red CI, so pairs land in reviewable batches without a big-bang PR. New documents are the exception — a date-named document dated on/after the manifest's `requiredSince` cutoff merges bilingual or not at all, so the backlog only ever shrinks.
 - The recorded hashes double as the update tool (`git cat-file -p <hash>` recovers either side's last-confirmed text for a minimal diff-based update), so re-translation of whole files is never forced by the mechanism.

docs/rfc/implemented/process/2026-07-02-bilingual-docs-and-pairing-gate.zh.md

@@ -32,5 +32,5 @@
 - 每个配对给目录树多添一个文件。记录由机器写入（`--write`），代价是目录噪音而非维护负担；换来的是「谁在何时确认过这对一致」可以从 yaml 的 git blame 直接回答。
 - 两侧说法冲突时，没有机械规则裁决谁赢——由 PR 评审裁决。这是同权的代价，是有意接受的：另一个选项（正典语言）禁止中文先行撰写。
 - 生成文档（`cordis-catalog/`、`tool-catalog/`、`module-graph.md`）暂被排除；计划中的后续工作是让它们的生成器在输出英文的同时输出中文，届时移出排除清单。
-- 推进天然是渐进的：`required` 之外的文档是可见的 backlog（`--list`），不是红的 CI，因此配对按可评审的批次落地，无需一个巨型 PR。
+- 推进天然是渐进的：`required` 之外的文档是可见的 backlog（`--list`），不是红的 CI，因此配对按可评审的批次落地，无需一个巨型 PR。新文档是例外——文件名日期在 manifest `requiredSince` 当天或之后的文档，要么连同配对一起合入，要么不合入，因此 backlog 只会缩小。
 - 记录的 hash 兼作更新工具（`git cat-file -p <hash>` 能还原任一侧上次确认的文本，用于基于 diff 的最小更新），所以这套机制从不强迫整篇重译。