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.

pnpm-lock.yaml

@@ -54,6 +54,9 @@ importers:
       '@anthropic-ai/claude-agent-sdk':
         specifier: ^0.3.159
         version: 0.3.159(@anthropic-ai/sdk@0.100.1(zod@3.25.76))(@modelcontextprotocol/sdk@1.29.0(zod@3.25.76))(zod@3.25.76)
+      '@boocode/contracts':
+        specifier: workspace:*
+        version: link:../../packages/contracts
       '@boocode/server':
         specifier: workspace:*
         version: link:../server
@@ -100,6 +103,9 @@ importers:
 
   apps/coder/web:
     dependencies:
+      '@boocode/contracts':
+        specifier: workspace:*
+        version: link:../../../packages/contracts
       lucide-react:
         specifier: ^1.16.0
         version: 1.16.0(react@18.3.1)
@@ -146,6 +152,9 @@ importers:
       '@ai-sdk/openai-compatible':
         specifier: ^2.0.47
         version: 2.0.47(zod@3.25.76)
+      '@boocode/contracts':
+        specifier: workspace:*
+        version: link:../../packages/contracts
       '@fastify/static':
         specifier: ^7.0.4
         version: 7.0.4
@@ -192,6 +201,9 @@ importers:
 
   apps/web:
     dependencies:
+      '@boocode/contracts':
+        specifier: workspace:*
+        version: link:../../packages/contracts
       '@fontsource-variable/inter':
         specifier: ^5.2.8
         version: 5.2.8
@@ -287,6 +299,19 @@ importers:
         specifier: ^5.3.4
         version: 5.4.21(@types/node@20.19.41)(lightningcss@1.32.0)
 
+  packages/contracts:
+    dependencies:
+      zod:
+        specifier: ^3.23.8
+        version: 3.25.76
+    devDependencies:
+      typescript:
+        specifier: ^5.5.0
+        version: 5.9.3
+      vitest:
+        specifier: ^3.2.4
+        version: 3.2.4(@types/debug@4.1.13)(@types/node@20.19.41)(lightningcss@1.32.0)(msw@2.14.6(@types/node@20.19.41)(typescript@5.9.3))
+
 packages:
 
   '@agentclientprotocol/sdk@0.22.1':