enh: timezone to conform iso8601 - main

[localvar]

Description

Extend timezone offset support from ±12:00 to ±14:00 (covering all real-world timezones including UTC+13, UTC+14, UTC+5:45, etc.) and implement the new TZ/tz format specifier for to_char/to_timestamp.

timezone validation (builtins.c)

• valid hour range extended from ±12 to ±14
• valid minute range extended to 0-59 (was restricted to 0/30 for specific hours), with guard for hour==14 requiring minute==0

timezone parsing (ttime.c)

• parseTimezone: extended hour limit to 14
• New TSFKW_TZ format specifier: outputs ±HH:MM in to_char, parses Z, ±HH, ±HH:MM, ±HHMM in to_timestamp
• Added tzMinute handling in char2ts for proper minute-level timezone offset application
• Refactor function keywordSearch to avoid using TSFormatKeywordIndex which is hard to maintain

tests

• test_fun_sca_to_iso8601.py: extended timezone coverage, moved valid cases from error list
• test_fun_sca_to_timestamp.py: added TZ format tests and roundtrip verification
• test_fun_sca_to_unixtimestamp.py: added extended timezone epoch roundtrip tests
• test_fun_sca_timezone.py: replaced commented-out error cases with proper valid/error cases
• test_query_sub_interval.py: added TZ format subquery tests

documentation

• English and Chinese docs: added TZ/tz format description, timezone range note for TO_ISO8601

Issue(s)

• Close/close/Fix/fix/Resolve/resolve:
  • https://project.feishu.cn/taosdata_td/feature/detail/6849686611
  • https://project.feishu.cn/taosdata_td/feature/detail/6491037879

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[Copilot]

Pull request overview

This PR enhances TDengine’s timezone handling to better conform to ISO-8601/RFC3339, expanding supported offset ranges and formats, adding a TZ/tz formatter token, and updating tests/docs accordingly.

Changes:

• Extend timezone offset parsing/validation to support Z, ±HH, ±HHMM, ±HH:MM, including fractional-hour offsets and the -14:00..+14:00 range.
• Add TZ/tz format keyword support for to_char / to_timestamp roundtrips (outputting +HH:MM).
• Expand scalar/query test coverage and update English/Chinese SQL function documentation.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
source/common/src/ttime.c	Adds TZ keyword parsing/formatting and updates timezone parsing/validation logic.
source/libs/function/src/builtins.c	Updates ISO8601 timezone argument validation for built-in functions.
test/cases/11-Functions/01-Scalar/test_fun_sca_to_unixtimestamp.py	Adds to_unixtimestamp tests for extended timezone offsets and compact formats.
test/cases/11-Functions/01-Scalar/test_fun_sca_to_timestamp.py	Adds to_timestamp tests for TZ parsing and roundtrip behavior with to_char.
test/cases/11-Functions/01-Scalar/test_fun_sca_to_iso8601.py	Expands to_iso8601 timezone parameter tests and invalid-range coverage.
test/cases/11-Functions/01-Scalar/test_fun_sca_timezone.py	Updates timezone insert/query tests for newly valid offsets and stricter invalid cases.
test/cases/09-DataQuerying/08-SubQuery/test_query_sub_interval.py	Adds subquery coverage for TZ formatting and to_timestamp(to_char(...)) roundtrips.
docs/zh/14-reference/03-taos-sql/22-function.md	Documents TZ/tz formatter and timezone offset range limits for TO_ISO8601.
docs/en/14-reference/03-taos-sql/22-function.md	Documents TZ/tz formatter and timezone offset range limits for TO_ISO8601.
.github/scripts/check_enum_append_only.py	Updates enum append-only checker to allow broader ignore matching for one enum.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[gemini-code-assist]

Code Review

This pull request adds support for the TZ timezone format in TO_CHAR and TO_TIMESTAMP, extends the valid timezone offset range to +/-14:00, and updates the enum check script to support wildcards. Changes include documentation updates, refactored timezone parsing, and an optimized keyword search. Review feedback identifies a critical race condition in the keyword index initialization and a potential integer overflow risk.