FRE-588: Fix IDOR vulnerabilities and security findings

H1: Add verifyScriptAccess/verifyRevisionAccess to all 14 revisions endpoints
H2: Add verifyProjectAccess to listScripts and searchScripts
M2: Add cascade delete for projectMembers on project deletion
M4: Replace plain Error throws with TRPCError for consistent error handling
M5: Use crypto.randomUUID for team ID generation (was Date.now + Math.random)
L1: Add 100KB content size limit on revision content
L2: Add unique constraint to script slug column
L3: Update hasProjectAccess middleware to check project membership

src/db/schema/scripts.ts

@@ -7,7 +7,7 @@ export const scripts = sqliteTable("scripts", {
     .notNull()
     .references(() => projects.id),
   title: text("title").notNull(),
-  slug: text("slug").notNull(),
+  slug: text("slug").notNull().unique(),
   genre: text("genre"),
   logline: text("logline"),
   status: text("status", { enum: ["draft", "revision", "final", "published"] }).notNull().default("draft"),