feat(config): wt config update pins [list] json-schema while unset

[max-sixty]

Wires the [list] json-schema nag into the standard config-update machinery, so the warning comes with the standard one-command fix.

wt config update now pins json-schema = 1 (the behavior-preserving choice) when the key is unset, via a new PendingDefault variant in DEPRECATION_RULES: applied on the update pass only — the load path must not pin, or an in-memory Some(1) would silence the nag — and scoped to user config through a ConfigFileKind enum threaded through detection in place of the old string labels. Two guards keep the pin honest: it stays inert when the system config layer already defines the key (a user-file pin would override a system-level = 2 and flip resolved output), and the nag's hint offers wt config update only when the same detection update runs would actually write the pin — a missing, unreadable, or malformed user config falls back to naming the manual setting.

The detection-equals-migration invariant holds with the warning relocated: the pin's warning fires at the JSON-emitting surface (resolve_json_schema) exactly when update would change the file, while config load stays quiet (DeprecationKind::is_pending_default filters it, and pin-only configs skip the warning-dedup machinery entirely), so wt switch users never see it. wt config show renders the pending pin's diff — including for empty config files — but keeps its TOML dump: a pin is additive, unlike a deprecation diff that supersedes the dump.

This departs from the plan reviewed in design/list-json-v2.md (#3357), which deferred the wt config update integration to the default flip. Deliberate tradeoff: users who run update during the window land pinned on schema 1 and will see the = 1 deprecation round after the flip; in exchange, the warning ships with its fixer.

Testing: unit tests pin the rule's iff (unset ⟺ update changes the file), kind scoping (System/Project inert, load pass inert), the PendingDefault-rule/kind coupling, and placement in existing or implicit [list] sections; integration tests cover both hint variants, the update flow end-to-end (pin applied, second run clean), --print, and the system-config deferral. The invariant battery runs with an explicit pin appended so each case exercises only its own rule. Full pre-merge gate green (4386 tests) plus --features shell-integration-tests clippy.

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This was written by Claude Code on behalf of max

[worktrunk-bot]

Reviewing as a draft — flagging anything that looks worth a quick fix. Mark ready for a full review.

The comment is accurate and reads well. One small pointer issue: design/list-json-v2.md won't resolve for a reader on any branch — design docs are removed from the net diff by repo convention, and #3357's own body pins this one to commit e1c9b72e0 ("it remains readable at e1c9b72"). As written, the bare path reads as a present file; a reader has to open #3357 to discover where it actually lives. Inline suggestion carries the SHA pin over so the reference is followable in one hop.