Complete TypeScript syntax remediation in legacy files

Scope

• Fix remaining ~3,096 TypeScript syntax errors in legacy code
• Ban = { method pattern with ESLint rule to prevent future violations
• Focus on deterministic passes (method signature syntax)

Done When

• npx tsc --noEmit passes repo-wide (zero errors)
• ESLint rule added to prevent method() = { pattern
• All legacy files use correct method() { syntax

Context

Already fixed 2,148 errors in previous work. Remaining errors are:

• Method signature syntax ()= { → ){)
• Template literal/object literal issues
• Stray comma-to-semicolon conversions needed

Strategy

Use gradual tsconfig approach: allow commits of NEW code while tracking legacy cleanup here.