feat: single-source cross-app wire contracts in @boocode/contracts (v2.7.13)

Move all hand-synced cross-app wire contracts into one built workspace
package, @boocode/contracts, consumed by server/web/coder/coder-web via
workspace:* + a per-subpath exports map. The ws-frames and provider-config
Zod schemas are schema-first (z.infer); MessageMetadata, ErrorReason,
AgentSessionConfig, the provider snapshot types, and WorktreeRiskReport are
each single-sourced. Deletes the byte-identical copies and their parity
tests, fixes a live AgentSessionConfig drift (coder dead copy removed,
unified to the web required/nullable shape), removes the dead pending_change
WS arms in the fallback SPA, and inverts the build order (contracts builds
first) across root build, Dockerfile, and the coder deploy docs. Reverses
the shared-package decision declined in v2.5.12.

packages/contracts/src/provider-snapshot.ts

@@ -0,0 +1,52 @@
+/** Provider snapshot types — single source of truth. Plain TS, no runtime. */
+
+export interface ProviderMode {
+  id: string;
+  label: string;
+  description?: string;
+  /** Auto-approve tool permissions when this mode is selected. */
+  isUnattended?: boolean;
+}
+
+export interface ThinkingOption {
+  id: string;
+  label: string;
+  isDefault?: boolean;
+}
+
+export interface ProviderModel {
+  id: string;
+  label: string;
+  description?: string;
+  isDefault?: boolean;
+  thinkingOptions?: ThinkingOption[];
+  defaultThinkingOptionId?: string;
+}
+
+// v2.3 phase 2: 'loading' (cache-miss, probe in flight) + 'unavailable'
+// (disabled or not installed) restored alongside the terminal 'ready' | 'error'.
+export type ProviderSnapshotStatus = 'loading' | 'ready' | 'unavailable' | 'error';
+
+export interface AgentCommand {
+  name: string;
+  description?: string;
+  // v2.5.11: 'skill' (plugin skill) vs 'command' (native/CLI slash command).
+  // Drives the icon split in the coder slash menu. Undefined → command.
+  kind?: 'command' | 'skill';
+}
+
+export interface ProviderSnapshotEntry {
+  name: string;
+  label: string;
+  description?: string;
+  transport: string;
+  status: ProviderSnapshotStatus;
+  enabled: boolean;
+  installed: boolean;
+  models: ProviderModel[];
+  modes: ProviderMode[];
+  defaultModeId: string | null;
+  commands: AgentCommand[];
+  error?: string;
+  fetchedAt?: string;
+}