docs(list): document pre-skeleton fork inventory

[max-sixty]

Consolidates the spec for what runs before the wt switch / wt list skeleton appears, since the previous "Fixed Command Count" table mixed logical fetches with actual forks (most of the listed commands are now cache hits served from the prewarmed in-memory config map) and didn't break down the git log --no-walk batch.

Two doc-only edits, no behavior change:

• commands/list/collect/mod.rs — replaced ### Fixed Command Count with ### Forks on the Critical Path: five git forks on the path to the skeleton for a normal repo (six in repos with extensions.worktreeConfig=true, where Repository::all_config re-forks from git_common_dir because --list from a linked worktree misses main-worktree config.worktree overrides). Each row carries its source method and role; Re-enable shell wrapper tests with correct fish snapshots #3 is explicitly tagged Conditional with the regime spelled out. A "looks like a fork but isn't" list enumerates the config_last lookups served from the in-memory map. A callout flags default_branch()'s one-per-repo git ls-remote fallback (worktrunk's one accepted wire-path exception per CLAUDE.md → "Network Access"). A new ### #6 — the batched commit-details fork subsection breaks down git log --no-walk --no-show-signature --format=%H%x00%h%x00%ct%x00%s field by field: which downstream cell each format field feeds, why each flag is there, the ARG_MAX bound on argv length.
• commands/picker/mod.rs — a one-sentence pointer onto the existing "Time-to-skeleton" line directing readers to the new collect section.

Verified locally with RUSTDOCFLAGS='-Dwarnings' cargo doc --no-deps --document-private-items (intra-doc links to Repository::prewarm, at, all_config, list_worktrees, local_branches, url_template, is_bare, default_branch all resolve).

🤖 Generated with Claude Code

[worktrunk-bot]

Two factual snags in the inventory — see inline. The bigger one is that fork #3 doesn't actually fire on the steady-state path for normal repos: Repository::at consumes GIT_CONFIG_PRELOAD (the parsed map from #2) into cache.all_config via .set() at src/git/repository/mod.rs:528-531, so the get_or_try_init inside all_config is a memory hit, not a fork. The prewarm_git_config docstring itself spells this out — all_config only re-forks "when the parsed map contains extensions.worktreeconfig=true" (src/git/repository/mod.rs:773-778). That makes the new "six forks on the critical path" headline an overcount for the typical case (it's five), and contradicts the "Things that look like forks but aren't" list below where Repository::is_bare is described as "served from #2's in-memory map" — which is only true because #3 didn't fire.

The other one is smaller: Repository::url_template isn't a config_last("…") lookup at all — it reads list.url from the worktrunk project config (.config/wt.toml, a TOML file read via load_project_config), not from git config. The "no fork" conclusion is still right but the explanation doesn't match the source.