feat(projects): list + create API and creatable ProjectAutocomplete (T4)

- GET /api/projects returns the shared global list; POST /api/projects
  creates a project, deduped case-insensitively (F3).
- Repository find-or-create trims and matches on lower(name); a unique index
  on lower(name) enforces the same rule at the DB (replacing the case-
  sensitive column unique constraint) — migration 0001.
- ProjectAutocomplete: creatable autocomplete that lists projects, offers to
  create an unknown name inline, and selects it without reload.
- Integration test (dedupe/list against Postgres) + component test.

server/db/schema.ts

@@ -1,14 +1,20 @@
 // Drizzle (Postgres) schema (C8).
 // `section_id` is a plain string referencing the in-code board section ids
 // (C1) — no foreign key, because sections live in code, not the DB (ADR 0001).
-import { pgTable, uuid, text, timestamp } from 'drizzle-orm/pg-core'
+import { pgTable, uuid, text, timestamp, uniqueIndex } from 'drizzle-orm/pg-core'
+import { sql } from 'drizzle-orm'
 import { randomUUID } from 'node:crypto'
 
-export const projects = pgTable('projects', {
-  id: uuid('id').primaryKey().$defaultFn(randomUUID),
-  name: text('name').notNull().unique(),
-  createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
-})
+export const projects = pgTable(
+  'projects',
+  {
+    id: uuid('id').primaryKey().$defaultFn(randomUUID),
+    name: text('name').notNull(),
+    createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+  },
+  // Case-insensitive uniqueness: "Acme" and "acme" are the same project (F3).
+  (t) => [uniqueIndex('projects_name_lower_idx').on(sql`lower(${t.name})`)],
+)
 
 export const defects = pgTable('defects', {
   id: uuid('id').primaryKey().$defaultFn(randomUUID),