chore: bump version to 0.9.74

[xiaolai]

Patch release. Bumps the five version files plus the derived src-tauri/Cargo.lock.

Ships since v0.9.73:

• fix: linear-time hostile markdown and handled nesting refusals (fixes #1407) #1415 — soak: hostile markdown input parses and serializes in linear time; a document the parser refuses opens in Source mode instead of a blank editor (fixes Soak workflow failed #1407)
• fix: run the soak fuzz's documented seed, and fix the editor bugs it hid #1416 — the weekly fuzz ran seed 0 instead of its documented seed; fixes the five editor bugs the real seed exposed (lost italics beside bold and emoji, lost strikethrough beside CJK punctuation, an empty nested list item turning into text, and undo corrupting history into a RangeError)
• fix: run both mutation tools in place so their baselines see the real tree (fixes #1409) #1410 — both mutation-testing baselines run again (fixes Mutation testing workflow failed #1409)
• fix(deps): bump rustls to 0.23.45 for RUSTSEC-2026-0285 #1412 — rustls 0.23.45 for RUSTSEC-2026-0285
• fix: keep shell scripts on LF line endings on every checkout #1411 — shell scripts and git hooks keep LF line endings on Windows checkouts