Prevent cross-worktree session bleed during managed session resume/load

ROADMAP #41 was still leaving a phantom-completion class open: managed
sessions could be resumed from the wrong workspace, and the CLI/runtime
paths were split between partially isolated storage and older helper
flows. This squashes the verified team work into one deliverable that
routes managed session operations through the per-worktree SessionStore,
rejects workspace mismatches explicitly, extends lane-event taxonomy for
workspace mismatch reporting, and updates the affected CLI regression
fixtures/docs so the new contract is enforced without losing same-
workspace legacy coverage.

Constraint: Keep same-workspace legacy flat sessions readable while blocking cross-worktree misuse
Constraint: No new dependencies; stay within the ROADMAP #41 changed-file scope
Rejected: Leave team auto-checkpoint history as final branch state | noisy/non-lore history for a single roadmap fix
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Preserve workspace_root validation on future resume/load helpers; do not reintroduce path-only fallback without equivalent mismatch checks
Tested: cargo test -p runtime session_control -- --nocapture; cargo test -p rusty-claude-cli resume -- --nocapture; cargo test -p rusty-claude-cli --test cli_flags_and_config_defaults; cargo test -p rusty-claude-cli --test output_format_contract; cargo test -p rusty-claude-cli --test resume_slash_commands; cargo test --workspace --exclude compat-harness; cargo check --workspace --all-targets; git diff --check
Not-tested: cargo clippy --workspace --all-targets -- -D warnings (pre-existing failures in unchanged rust/crates/rusty-claude-cli/build.rs)
Related: ROADMAP #41

rust/crates/tools/src/lib.rs

@@ -3734,6 +3734,8 @@ fn classify_lane_failure(error: &str) -> LaneFailureClass {
         || normalized.contains("tool runtime")
     {
         LaneFailureClass::ToolRuntime
+    } else if normalized.contains("workspace") && normalized.contains("mismatch") {
+        LaneFailureClass::WorkspaceMismatch
     } else if normalized.contains("plugin") {
         LaneFailureClass::PluginStartup
     } else if normalized.contains("mcp") && normalized.contains("handshake") {
@@ -7253,6 +7255,10 @@ mod tests {
                 "tool failed: denied tool execution from hook",
                 LaneFailureClass::ToolRuntime,
             ),
+            (
+                "workspace mismatch while resuming the managed session",
+                LaneFailureClass::WorkspaceMismatch,
+            ),
             ("thread creation failed", LaneFailureClass::Infra),
         ];
 
@@ -7279,6 +7285,10 @@ mod tests {
                 LaneEventName::BranchStaleAgainstMain,
                 "branch.stale_against_main",
             ),
+            (
+                LaneEventName::BranchWorkspaceMismatch,
+                "branch.workspace_mismatch",
+            ),
         ];
 
         for (event, expected) in cases {