fix(12306): accept lowercase letters in train_no regex

[dusty-cjh]

Problem

The 12306 leftTicket API sometimes returns train_no values that contain lowercase letters. For example, querying 上海 → 宝鸡 on 2026-05-25 returns this for G1970:

train_no: 5l000G1970A3   # note the lowercase "l"
code: G1970
from_station: 上海虹桥
to_station: 宝鸡南

12306 trains outputs the value verbatim, but feeding it back into the documented next step fails locally before ever hitting 12306:

$ opencli 12306 price 5l000G1970A3 --from AOH --to BBY --date 2026-05-25
ok: false
error:
  code: ARGUMENT
  message: <train-no> "5l000G1970A3" does not look like a 12306 internal train_no
  help: Use the train_no field from `12306 trains` output (e.g. 24000000G10L), not the public code (G1).
  exitCode: 2

Same failure on 12306 train. Root cause: TRAIN_NO_RE = /^[0-9A-Z]{8,18}$/ in both price.js and train.js is stricter than what 12306 actually emits. Capitalising the l to L passes the regex but then returns EMPTY_RESULT from 12306 — confirming the canonical id really is lowercase.

The error help text is also misleading: it tells the user to use the value from 12306 trains output, which is exactly what they did.

Fix

Widen the regex to /^[0-9A-Za-z]{8,18}$/ in both adapters. Verified end-to-end after the change:

$ opencli 12306 price 5l000G1970A3 --from AOH --to BBY --date 2026-05-25
- seat_code: A9
  seat_name: 商务座
  price: '2611.0'
- seat_code: M
  seat_name: 一等座
  price: '1252.0'
- seat_code: O
  seat_name: 二等座
  price: '768.0'
  ...

Tests

Added a parameterised describe block in clis/12306/utils.test.js that pins both regexes (price + train) against:

• the historical uppercase example 24000000G10L (must accept)
• the lowercase real-world value 5l000G1970A3 (must accept — regression)
• public codes like G1970 (must reject)
• values containing punctuation 5l000-G1970A3 (must reject)

Test Files  1 passed (1)
     Tests  39 passed (39)

npx tsc --noEmit clean.

Notes

• Only the format regex changed; everything downstream (URL building, 12306 API contract) already round-trips the value as an opaque string.
• SEAT_TYPES_RE is intentionally left untouched — seat-type letters are a small, well-known uppercase set defined by 12306.

[Copilot]

Pull request overview

This PR aligns OpenCLI’s 12306 adapters with real-world leftTicket payloads by relaxing the internal train_no validation to accept lowercase letters, preventing local ARGUMENT failures when users paste values emitted by 12306.

Changes:

• Widened TRAIN_NO_RE in both clis/12306/price.js and clis/12306/train.js to allow [A-Za-z].
• Exposed TRAIN_NO_RE in price.js test exports and added parameterized tests to pin behavior for both adapters.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
clis/12306/utils.test.js	Adds regression coverage ensuring both adapters accept lowercase-containing train_no values and still reject public codes/invalid chars.
clis/12306/train.js	Updates TRAIN_NO_RE to accept lowercase letters for real 12306 train_no values.
clis/12306/price.js	Updates TRAIN_NO_RE to accept lowercase letters and exports it via __test__ for validation tests.

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