ticket: simplify ticket identity fields

.yoi/tickets/20260608-103842-001/resolution.md

@@ -0,0 +1,20 @@
+Implemented and merged.
+
+Summary:
+- Removed `legacy_ticket` from the current Ticket schema, metadata, summary, tool input/output, and CLI show/list/create surfaces.
+- Removed `needs_preflight` from current schema/API/panel/tool output surfaces.
+- Removed legacy `workflow_state: intake` compatibility; parser/tests now reject `intake` instead of normalizing it to `planning`.
+- Migrated local `.yoi/tickets/**/item.md` frontmatter to remove obsolete `legacy_ticket` entries, including non-null values explicitly authorized as obsolete migration breadcrumbs.
+- Preserved historical thread/resolution prose as audit history where it is not current schema/API input.
+
+Implementation:
+- Coder commit: `934a4b5 ticket: remove legacy schema fields`
+- Merge commit: `de8e973 merge: remove legacy ticket schema fields`
+- Reviewer approved with no blocking findings.
+
+Validation:
+- `cargo fmt --check`
+- `git diff --check`
+- `cargo run -q -p yoi -- ticket doctor`
+- `cargo check --workspace`
+- `nix build .#yoi`