chore(release): bump version to 0.12.5

[ahilles107]

What

Bumps the release version to 0.12.5 across the four manifests the release
workflow checks (Cargo.toml, apps/desktop/src-tauri/Cargo.toml,
apps/desktop/package.json, apps/desktop/src-tauri/tauri.conf.json) and
syncs both lockfiles.

Why

Cuts a release for everything that landed since v0.12.4. It is all fixes and
docs/tooling — no new surface, nothing removed, no changed default — so this is
a patch bump:

• fix(desktop): keep terminal scroll position across bot switches #7 — terminal keeps its scroll position across bot switches
• docs(workflow): use GitHub Issues for internal work #6 — internal work tracked in GitHub Issues
• fix(skills): make contributor workflows safe and portable #4 — contributor skills made safe and portable

How tested

• cargo update --workspace --offline in both workspaces; only the local
  crate versions moved, so neither lockfile is dirtied by the release build.
• Confirmed all four manifests read 0.12.5, which is what the release
  workflow's Resolve version step asserts against the v0.12.5 tag.
• CI checks and tests on this PR.