NewSession and ClearSession reset the executor session, planner,
guardian, and checkpoints — but not the goal machine. A running goal's
text (plus its autoresearch runtime block) kept injecting into the
fresh session's first turns, silently steering a conversation the user
had explicitly reset.

Controller: both rotations now ClearGoal() after rebindCheckpoints has
moved the goal-state path to the fresh session, so the cleared
(stopped) state lands on the NEW path while the old session's sidecar —
persisted before the rotation — keeps its running goal for /resume.
This covers every frontend (typed /new, CLI, serve, bot, desktop).

Desktop: the tab's persisted goal copy follows the controller —
App.NewSession and ClearSession clear tab.goal (otherwise the next
rebuild or restart would re-seed the old goal via SetGoal(tab.goal)),
and clearActiveSessionRuntime no longer seeds the destroyed
conversation's goal into the replacement controller. The model/effort/
settings rebuild paths keep the goal: those are same-session rebuilds.

TestSessionRotationClearsActiveGoal pins all four properties: goal
empty and no <active-goal> injection after /new and /clear, the old
session's sidecar keeps the running goal, and the new session's sidecar
does not carry it. Verified it fails without the ClearGoal calls.

Review catch: a typed /new or /clear rotates the session through the
controller slash path and never reaches App.NewSession/ClearSession, so
desktop-tabs.json can keep the pre-rotation goal. On the next restart,
restoreOrBuildTabs read entry.Goal unfiltered and the tab build seeded
it into the rotated session via SetGoal(buildGoal) — resurrecting the
goal the rotation had cleared. (The goal-state filter I pointed at in
the PR description only runs on the runtime-profile path, not startup
restore.)

Restore now validates entry.Goal through runningTabSessionGoal: the
rotation writes a stopped goal-state sidecar onto the fresh path, so a
restart reads stopped → no goal; a tab still pointing at the old
session reads running → goal preserved (resume semantics); a session
without a sidecar keeps the persisted goal (legacy).

TestRestoredTabGoalFollowsSessionGoalState pins the cross-layer
contract with a real controller rotation: rotated path → cleared, old
path → preserved, no sidecar → fallback.