feat: consolidate web auth and add Effect v4 Project primitives

Auth:
- Add useWebAuth hook as the single web-facing auth interface with four
  states (loading/unauthenticated/authenticated/inconsistent)
- Normalize getCurrentUser to return {id: tokenIdentifier, name, email}
- Rename requireOwnerId to requireAuthUserId across all backend callers
- Set expectAuth:true on ConvexReactClient singleton
- Migrate _app, _auth, user-menu, use-personal-organization to useWebAuth
- Remove unused @code/auth/server export (zero callers confirmed)

Primitives:
- Add packages/primitives/src/project.ts with Effect v4 Project domain:
  URL normalization, six canonical context kinds, strict remote decoding,
  context write decisioning with revision tracking, and no-op detection
- Define PublicGit and ProjectStore replaceable ports
- Define ProjectApplication service orchestrating domain+ports with
  deterministic error mapping
- Add comprehensive test suite (28 tests) with in-memory store and fake
  PublicGit covering normalization, seeds, idempotency, tenant isolation,
  last-write-wins, and typed error mapping

packages/backend/convex/projects.ts

@@ -5,7 +5,7 @@ import { internal } from "./_generated/api";
 import type { Id } from "./_generated/dataModel";
 import { action, internalMutation, query } from "./_generated/server";
 import { createInitialArtifacts } from "./artifactModel";
-import { requireOwnerId } from "./authz";
+import { requireAuthUserId } from "./authz"
 
 const gitHubRepositorySchema = z.object({
   default_branch: z.string(),
@@ -47,7 +47,7 @@ const readGitHubRepository = (value: unknown) => {
 export const connectGitHub = action({
   args: { repository: v.string() },
   handler: async (ctx, args): Promise<Id<"projects">> => {
-    const ownerId = await requireOwnerId(ctx);
+    const ownerId = await requireAuthUserId(ctx);
     const { owner, repo } = parseRepository(args.repository);
     const response = await fetch(
       `https://api.github.com/repos/${owner}/${repo}`,
@@ -157,7 +157,7 @@ export const storeGitHubProject = internalMutation({
 export const list = query({
   args: {},
   handler: async (ctx) => {
-    const ownerId = await requireOwnerId(ctx);
+    const ownerId = await requireAuthUserId(ctx);
     return await ctx.db
       .query("projects")
       .withIndex("by_owner_and_createdAt", (q) => q.eq("ownerId", ownerId))
@@ -169,7 +169,7 @@ export const list = query({
 export const get = query({
   args: { projectId: v.id("projects") },
   handler: async (ctx, args) => {
-    const ownerId = await requireOwnerId(ctx);
+    const ownerId = await requireAuthUserId(ctx);
     const project = await ctx.db.get("projects", args.projectId);
     return project?.ownerId === ownerId ? project : null;
   },