perf: add database indexes to commonly queried entity fields

[sameh-farouk]

Summary

Fixes #216. Adds 25 database indexes across 9 entities based on analysis of actual query patterns from all downstream consumers.

Research

Analyzed GraphQL queries and direct SQL access across:

• tfgrid-sdk-ts (grid_client, playground, dashboard) — direct GraphQL queries
• tfgrid-sdk-go (grid-client, relay-cache-warmer) — direct GraphQL queries
• grid-proxy — reads the processor's PostgreSQL directly via GORM/SQL (does NOT use GraphQL API)

Grid-proxy already creates some indexes in its setup.sql, but they get lost on processor DB reset. This PR makes them part of the processor's migration.

Full research details in #216 comments.

Indexed fields (25 total)

Entity	Fields
Twin	twinID
Farm	farmID, name, twinID, dedicatedFarm
PublicIp	ip
Node	nodeID, farmID, twinID, certification
NodeContract	contractID, twinID, nodeID, state
NameContract	contractID, twinID, state
RentContract	contractID, twinID, nodeID, state
ContractBillReport	contractID, timestamp
UptimeEvent	nodeID, timestamp

What changed

• schema.graphql — added @index directive to 25 fields
• src/model/generated/*.model.ts — regenerated by yarn codegen with @Index_() decorators
• db/migrations/1775123913074-Data.js — new migration with 25 CREATE INDEX statements

Backward compatibility

• No table/column changes — migration contains only CREATE INDEX statements
• Grid-proxy's setup.sql indexes use CREATE INDEX IF NOT EXISTS — they coexist without conflict
• No processor reindex needed — indexes are added to existing data

Test plan

• yarn build passes
• Migration generated with exactly 25 CREATE INDEX statements, no other alterations
• Apply migration on dev/qa and verify query performance improvement

[sameh-farouk]

Tetsed on test vm
Test VM is consistently faster across all queries. The standout is ContractBillReports by contractID: 4.3x faster (177ms vs 754ms) that's the 8.2M row table where the index makes the biggest difference.
The general 1.6x improvement across all queries is likely a combination of the DB indexes, and The network latency difference (prod is behind HTTPS) also plays a role, But the contractBillReports result (4.3x) is clearly index-driven.