ci: bump pinned worktrunk to 0.79.0

[worktrunk-bot]

Weekly CI pin bump: worktrunk =0.78.0 → =0.79.0, at three sites (ci.yaml ×2, nightly.yaml).

This is the wt that runs the suite (wt hook pre-merge) on all three platforms, so it has its own PR: this PR's CI matrix is the only place the bump gets tested. This week's other drifted pins (cargo-nextest and Nushell) are in their own PRs.

Compatibility: worktrunk 0.79.0 declares rust-version = 1.97, which matches the pinned toolchain (rust-toolchain.toml channel 1.97.0).

Neither of 0.79.0's two breaking changes reaches CI. CI calls wt only as wt hook pre-merge --yes <filters>. The breaking changes are to wt switch --no-cd -x (the program now runs in the new worktree) and to wt merge/wt step rebase, which now pass --no-update-refs. CI invokes none of those commands.

Weekly checks that found no drift

• MSRV/toolchain: current stable is 1.98.1, so latest−1 is 1.97, which Cargo.toml, tests/helpers/wt-perf/Cargo.toml, and rust-toolchain.toml already pin. The nightly-2026-08-01 pins in nightly.yaml are about 8 weeks old, inside the three-month window. With no toolchain change, flake.lock needed no refresh.
• Other cargo-install pins: cargo-affected 0.4.1, cargo-insta 1.48.0, cargo-llvm-cov 0.9.1, cargo-msrv 0.19.3, cargo-udeps 0.1.61, and lychee 0.24.2 all match their current crates.io releases.
• Codex Cloud tools: PowerShell 7.6.6 is still the latest PowerShell/PowerShell release. cloud.sh's cargo-nextest and Nushell pins move in the sibling PRs.
• Runner images: ubuntu-24.04, macos-26, and windows-2025 each still match their -latest label in the actions/runner-images table, and ubuntu-24.04-arm and macos-26-intel follow those rows. Xcode 27 is still badged preview.
• dependabot.yaml typescript ignore: @astrojs/check still declares typescript ^5.0.0 || ^6.0.0, so the major-version ignore entry stays (fix(docs): pin typescript to ^6 so npm ci resolves #3877).
• LLM model pins: claude-haiku-4.5 is still the current Haiku, and gpt-6-luna is what the Codex models page calls "our most efficient model".
• Statusline cache-check: clean. wt config state logs profile reports same_context_duplicates: [] on a wt list statusline --format=claude-code render.
• Agent integration surfaces: nothing to flag. Claude Code 2.1.280–2.1.283 made no statusline schema change and no WorktreeCreate/WorktreeRemove change. Its new claude plugin validate checks (marketplace names it can't install, unquoted ${CLAUDE_PLUGIN_ROOT} in shell-form hooks) pass for our manifest: the marketplace and plugin are both named worktrunk, and every hook quotes "$CLAUDE_PLUGIN_ROOT/...". Codex rust-v0.156.x–0.157.1, Gemini CLI v0.61.0, and OpenCode v1.18.32 change nothing in the marketplace, extension, or plugins API.
• README date stamp: already September 2026.
• Dependency PRs: none open.