Related: #93397

What Problem This Solves

Fixes an issue where users who supplied an invalid MiniMax TTS volume directive saw a warning that described both range endpoints as exclusive, even though MiniMax and OpenClaw accept 10 and reject only values at or below 0 or above 10.

Why This Change Was Made

The warning now states the boundary in plain language: volume must be greater than 0 and at most 10. Exact boundary tests cover rejected values 0 and 11, preserve acceptance of 10, and the public TTS directive reference now uses the canonical (0, 10] notation.

This is a maintainer replacement for #93397 because the contributor branch was based far behind current main; refreshing that fork through GitHub's verified-commit API would have required replaying thousands of unrelated files. The useful contributor change is preserved with co-author credit.

User Impact

MiniMax TTS users now receive an accurate, unambiguous volume warning and see the same boundary in the TTS documentation. Numeric parsing and synthesis behavior are unchanged.

Evidence

• Current MiniMax T2A HTTP documentation declares voice_setting.vol as (0, 10] with exclusiveMinimum: 0 and maximum: 10.
• Focused regression coverage asserts the exact warning for vol=0 and vol=11, while vol=10 remains accepted without a warning.
• Fresh Codex autoreview on the current-main diff reported no accepted/actionable findings.
• Blacksmith Testbox through Crabbox tbx_01kwxe0113trnv147sx2kb4j27 (Actions run 28841981897): pnpm test extensions/minimax/speech-provider.test.ts passed 39 tests; pnpm check:changed passed.
• Repo-native prepare verified exact head 6d02a4ab2db5414c70d65eb0966ad822b0d5ed68 against hosted CI/Testbox gates.