feat: generic project UI, branding fix, context/artifact separation

Web:
- Replace GitHub-specific import with generic public Git URL import
- Update project workspace page to use ProjectView shape (name, sources)
- Migrate use-project-workspace hook to importPublicGit action
- Fix status key needsInput → needs-input

Branding:
- Correct Zopo/zopo → Zopu/zopu in docs/PRODUCT.md, docs/DESIGN.md, docs/TECH.md

Artifacts:
- Cut to 8 operational artifacts (removed project/business/design.md)
- Update artifact seeds with generic context scaffolding

packages/backend/convex/projects.ts

@@ -1,8 +1,6 @@
 import { v } from "convex/values";
-
 import {
   preparePublicGitSource,
-  decodePublicGitImportResult,
   type ProjectImportOutcome,
   type ProjectView,
   type PublicGitImportResult,
@@ -11,7 +9,6 @@ import {
 import { Effect } from "effect";
 
 import type { Id } from "./_generated/dataModel";
-import { internal } from "./_generated/api";
 import { action, internalMutation, query } from "./_generated/server";
 import { requireCurrentOrganization } from "./authz";
 import { createInitialArtifacts } from "./artifactModel";