fix(ticket): project immutable results and typed source observations

T-716: merged evidence uses recorded result approval; open source reads use Runtime provider authority and preserve unavailability. Current requirements use the shared exact snapshot evaluator. Remove primary-MR/report SQL heuristics; continue bounded query scans through nonmatching candidates. Align Worker/Web projections and explain lifecycle versus integration/attestation. Synchronize checker test on delivered inputs, not pre-delivery attempt state.

Validation: root cargo check; cargo test -p merge-request (30), -p server-api (70), -p worker (949), -p yoi-workspace-server (620 lib + 11 binary); server-api typescript feature check; 32 focused Deno tests; deno task check (0 errors/warnings); cargo fmt --all -- --check; git diff --check HEAD; canonical OpenAPI/generated Ticket artifact checks.

crates/server-api/src/lib.rs

@@ -7404,6 +7404,15 @@ pub struct TicketActionEligibility {
     pub blockers: Vec<String>,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(tag = "status", rename_all = "snake_case", deny_unknown_fields)]
+pub enum TicketSourceRefObservation {
+    Observed {},
+    Unavailable { code: String },
+    NotRequired {},
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[serde(deny_unknown_fields)]
@@ -7416,6 +7425,8 @@ pub struct TicketMergeRequestSummary {
     pub selector_to: String,
     pub updated_at: String,
     pub current_subject_ref: Option<String>,
+    pub source_ref_observation: TicketSourceRefObservation,
+    pub integration_evidence_error: Option<String>,
     pub review_subject_ref: Option<String>,
     pub review_requested_at: Option<String>,
     pub review_submitted_at: Option<String>,