RainTitle validator message claims 'alphanumeric ASCII letters and spaces' but the regex accepts all printable ASCII and rejects edge spaces #236

RainTitle's validator message (crates/cli/src/meta/types/common/v1.rs:47-53 at bba50a7) reads:

Must be alphanumeric ASCII letters and spaces.

Neither the regex nor the doc comment agrees with that message. REGEX_RAIN_TITLE (lines 21-25) is:

/// Titles in Rain are limited to printable ASCII chars and the space character.
/// The title MUST NOT begin or end with a space.
Regex::new(r"^[!-~]([ -~]*[!-~]|[!-~]*)$")

Actual accepted language: any printable ASCII (letters, digits, punctuation — "#1: hello!" is valid), interior spaces allowed, no leading/trailing space, non-empty. The message a user sees on rejection claims a much narrower contract ("alphanumeric letters and spaces") and omits the real constraints that most often trigger rejection (leading/trailing space, empty string).

Fix is a one-line message change, e.g. "Must be printable ASCII, not beginning or ending with a space." — or, if the message reflects the intended contract, the regex is too loose instead.

Found during round-2 adversarial mutation testing.