feat: add frontend TypeScript types and IPC layer

Establishes type-safe communication between React frontend and Rust backend.
Types mirror the Rust structs to ensure consistency across the Tauri boundary.

Type definitions (src/lib/types.ts):
- LoreStatus, LoreSummaryStatus: Lore CLI response shapes
- BridgeStatus, SyncResult: Bridge operation results
- McError, McErrorCode: Structured error handling with type guard
- FocusItem, FocusItemType: THE ONE THING work items
- FocusAction, DecisionEntry: User action tracking
- Staleness computation: fresh/normal/amber/urgent based on age

IPC wrapper (src/lib/tauri.ts):
- Typed invoke() calls for each Rust command
- getLoreStatus, getBridgeStatus, syncNow, reconcile, quickCapture

Data transformation (src/lib/transform.ts):
- transformLoreData: Converts lore response to FocusItem[]
- Priority ordering: reviews first (blocking others), issues, authored MRs
- Generates stable IDs matching bridge mapping keys

Formatting utilities (src/lib/format.ts):
- formatIid: Prefix with ! for MRs, # for issues

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/lib/types.ts

@@ -0,0 +1,132 @@
+/**
+ * TypeScript types mirroring the Rust backend data structures.
+ *
+ * These are used by the IPC layer and components to maintain
+ * type safety across the Tauri boundary.
+ */
+
+// -- Backend response types (match Rust structs in commands/mod.rs) --
+
+export interface LoreStatus {
+  last_sync: string | null;
+  is_healthy: boolean;
+  message: string;
+  summary: LoreSummaryStatus | null;
+}
+
+export interface LoreSummaryStatus {
+  open_issues: number;
+  authored_mrs: number;
+  reviewing_mrs: number;
+}
+
+export interface BridgeStatus {
+  mapping_count: number;
+  pending_count: number;
+  suspect_count: number;
+  last_sync: string | null;
+  last_reconciliation: string | null;
+}
+
+export interface SyncResult {
+  created: number;
+  closed: number;
+  skipped: number;
+  /** Number of suspect_orphan flags cleared (item reappeared) */
+  healed: number;
+  /** Error messages from non-fatal errors during sync */
+  errors: string[];
+}
+
+// -- Structured error types (match Rust error.rs) --
+
+/** Error codes for programmatic handling */
+export type McErrorCode =
+  | "LORE_UNAVAILABLE"
+  | "LORE_UNHEALTHY"
+  | "LORE_FETCH_FAILED"
+  | "BRIDGE_LOCKED"
+  | "BRIDGE_MAP_CORRUPTED"
+  | "BRIDGE_SYNC_FAILED"
+  | "BEADS_UNAVAILABLE"
+  | "BEADS_CREATE_FAILED"
+  | "BEADS_CLOSE_FAILED"
+  | "IO_ERROR"
+  | "INTERNAL_ERROR";
+
+/** Structured error from Tauri IPC commands */
+export interface McError {
+  code: McErrorCode;
+  message: string;
+  recoverable: boolean;
+}
+
+/** Type guard to check if an error is a structured McError */
+export function isMcError(err: unknown): err is McError {
+  return (
+    typeof err === "object" &&
+    err !== null &&
+    "code" in err &&
+    "message" in err &&
+    "recoverable" in err
+  );
+}
+
+/** Result from the quick_capture command */
+export interface CaptureResult {
+  bead_id: string;
+}
+
+// -- Frontend-only types --
+
+/** The type of work item surfaced in the Focus View */
+export type FocusItemType = "mr_review" | "issue" | "mr_authored" | "manual";
+
+/** A single work item that can be THE ONE THING */
+export interface FocusItem {
+  /** Unique key matching bridge mapping (e.g., "mr_review:g/p:847") */
+  id: string;
+  /** Human-readable title */
+  title: string;
+  /** Type badge to display */
+  type: FocusItemType;
+  /** Project path (e.g., "platform/core") */
+  project: string;
+  /** URL to open in browser (GitLab link) */
+  url: string;
+  /** Entity IID (e.g., MR !847, Issue #42) */
+  iid: number;
+  /** ISO timestamp of last update */
+  updatedAt: string | null;
+  /** Optional context quote (e.g., reviewer comment) */
+  contextQuote: string | null;
+  /** Who is requesting attention */
+  requestedBy: string | null;
+}
+
+/** Action the user takes on a focused item */
+export type FocusAction = "start" | "defer_1h" | "defer_tomorrow" | "skip";
+
+/** An entry in the decision log */
+export interface DecisionEntry {
+  timestamp: string;
+  action: FocusAction;
+  itemId: string;
+  reason: string | null;
+}
+
+/** Staleness level derived from item age */
+export type Staleness = "fresh" | "normal" | "amber" | "urgent";
+
+/** Compute staleness from an ISO timestamp */
+export function computeStaleness(updatedAt: string | null): Staleness {
+  if (!updatedAt) return "normal";
+
+  const ageMs = Date.now() - new Date(updatedAt).getTime();
+  const ageDays = ageMs / (1000 * 60 * 60 * 24);
+
+  if (ageDays < 1) return "fresh";
+  if (ageDays < 3) return "normal";
+  if (ageDays < 7) return "amber";
+  return "urgent";
+}