feat(mail): support gzip compressed email storage via ENABLE_MAIL_GZIP (#933)

* feat(mail): support gzip compressed email storage in D1 raw_blob column

Add ENABLE_MAIL_GZIP env var to optionally gzip-compress incoming emails
into a new raw_blob BLOB column, saving D1 storage space. Reading is
backward-compatible: prioritizes raw_blob (decompress) with fallback to
plaintext raw field. Includes DB migration v0.0.7, docs, and changelogs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: gzip fallback on missing column + decouple resolve from handleListQuery

- email/index.ts: gzip INSERT failure now falls back to plaintext INSERT
  instead of silently losing the email (P1: data loss prevention)
- common.ts: add handleMailListQuery for raw_mails-specific list queries
  with resolveRawEmailList, keeping handleListQuery generic
- Replace handleListQuery → handleMailListQuery in mails_api, admin_mail_api,
  user_mail_api (only raw_mails callers)
- Add e2e test infrastructure: worker-gzip service, wrangler.toml.e2e.gzip,
  api-gzip playwright project, mail-gzip.spec.ts with 4 test cases

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: address CodeRabbit review feedback for gzip feature

- Use destructuring in resolveRawEmailRow to truly remove raw_blob key
- Narrow fallback scope: only fallback to plaintext on compression failure
  or missing raw_blob column, re-throw other DB errors
- Clean unused imports in e2e gzip test

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: add try-catch in resolveRawEmail to prevent single corrupt blob from failing entire list

A corrupted raw_blob would cause decompressBlob to throw, which with
Promise.all in resolveRawEmailList would reject the entire batch query.
Now catches decompression errors and falls back to row.raw field.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mail): align sendAdminInternalMail with gzip storage path

sendAdminInternalMail now respects ENABLE_MAIL_GZIP: compresses to
raw_blob when enabled, with fallback to plaintext on failure.
Added e2e test verifying admin internal mail is readable under gzip.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(e2e): match admin internal mail by body content instead of encoded subject

mimetext base64-encodes the Subject header, so the raw MIME string
does not contain the literal subject text. Match on body content
(balance: 99) which is plaintext.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(e2e): add WORKER_GZIP_URL guard and length assertions in gzip tests

Address CodeRabbit feedback:
- Skip gzip tests when WORKER_GZIP_URL is not set to prevent false positives
- Assert results array length before accessing [0] for clearer error messages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mail): narrow gzip fallback scope and fix webhook query compatibility

- sendAdminInternalMail: separate compress vs DB error handling, only
  fallback to plaintext on compression failure or missing raw_blob
  column, rethrow other DB errors (aligns with email/index.ts)
- Webhook test endpoints: use SELECT * instead of explicit raw_blob
  column reference, so pre-migration databases don't 500
- Docs/changelog: clarify that db_migration must run before enabling
  ENABLE_MAIL_GZIP

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(telegram): use generic Record type for raw_mails query result

Align with other query sites — avoid hardcoding raw_blob in the
TypeScript type annotation so the query works with or without the
column after migration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(models): add RawMailRow type and unify raw_mails query typing

Add RawMailRow type to models with raw_blob as optional field, replacing
ad-hoc Record<string, unknown> and inline type annotations across
webhook test endpoints, telegram API, and gzip utilities.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -16,6 +16,7 @@
 - feat: |自动回复| 发件人过滤支持正则表达式匹配，使用 `/pattern/` 语法（如 `/@example\.com$/`），同时保持前缀匹配的向后兼容
 - feat: |Turnstile| 新增全局登录表单 Turnstile 人机验证，通过 `ENABLE_GLOBAL_TURNSTILE_CHECK` 环境变量控制（#767）
 - feat: |Telegram| Telegram 推送支持发送邮件附件（单文件限制 50MB），多附件通过 `sendMediaGroup` 批量发送，通过 `ENABLE_TG_PUSH_ATTACHMENT` 环境变量开启（#894）
+- feat: |邮件存储| 支持 Gzip 压缩存储邮件原文到 D1 数据库 `raw_blob` 字段，通过 `ENABLE_MAIL_GZIP` 环境变量开启，兼容已有明文 `raw` 字段的双字段读取。**启用前需先执行数据库迁移**（#823）
 
 ### Bug Fixes