refactor: migrate kraiken-lib to explicit subpath imports (BREAKING CHANGE) (#89)

Removes the barrel export pattern in favor of explicit subpath imports
for better tree-shaking and clearer dependencies.

## Breaking Changes
- Removed `src/helpers.ts` barrel export
- Removed `./helpers` from package.json exports
- Root `kraiken-lib` import now raises build errors
- Consumers MUST use explicit subpaths:
  - `kraiken-lib/abis` - Contract ABIs
  - `kraiken-lib/staking` - Staking helpers
  - `kraiken-lib/snatch` - Snatch selection
  - `kraiken-lib/ids` - Position ID utilities
  - `kraiken-lib/subgraph` - Byte conversion utilities
  - `kraiken-lib/taxRates` - Tax rate constants
  - `kraiken-lib/version` - Version validation

## Changes
- kraiken-lib:
  - Bumped version to 1.0.0 (breaking change)
  - Updated src/index.ts to raise build errors
  - Added backward-compatible ABI aliases (KraikenAbi, StakeAbi)
  - Updated all test files to use .js extensions and new imports
  - Updated documentation (README, AGENTS.md)

- Consumer updates:
  - services/ponder: Updated ponder.config.ts to use kraiken-lib/abis
  - web-app: Updated all imports to use subpaths
    - composables/usePositions.ts: kraiken-lib/subgraph
    - contracts/harb.ts: kraiken-lib/abis
    - contracts/stake.ts: kraiken-lib/abis

## Migration Guide
```typescript
// OLD
import { getSnatchList } from 'kraiken-lib/helpers';
import { KraikenAbi } from 'kraiken-lib';

// NEW
import { getSnatchList } from 'kraiken-lib/snatch';
import { KraikenAbi } from 'kraiken-lib/abis';
```

Fixes #86

Co-authored-by: openhands <openhands@all-hands.dev>
Reviewed-on: https://codeberg.org/johba/harb/pulls/89

tests/setup/stack.ts

@@ -2,15 +2,39 @@ import {
   runAllHealthChecks,
   formatHealthCheckError,
 } from './health-checks.js';
+import { readFileSync } from 'fs';
+import { join } from 'path';
 
 const DEFAULT_RPC_URL = 'http://localhost:8081/api/rpc';
 const DEFAULT_WEBAPP_URL = 'http://localhost:8081';
 const DEFAULT_GRAPHQL_URL = 'http://localhost:8081/api/graphql';
 
+export interface ContractAddresses {
+  Kraiken: string;
+  Stake: string;
+  LiquidityManager: string;
+}
+
 export interface StackConfig {
   rpcUrl: string;
   webAppUrl: string;
   graphqlUrl: string;
+  contracts: ContractAddresses;
+}
+
+/**
+ * Load contract addresses from deployments file
+ */
+function loadContractAddresses(): ContractAddresses {
+  try {
+    const deploymentsPath = join(process.cwd(), 'onchain', 'deployments-local.json');
+    const deploymentsJson = readFileSync(deploymentsPath, 'utf-8');
+    const deployments = JSON.parse(deploymentsJson);
+    return deployments.contracts;
+  } catch (error) {
+    console.error('Failed to load contract addresses from deployments-local.json:', error);
+    throw new Error('Cannot run tests without deployed contract addresses');
+  }
 }
 
 /**
@@ -22,6 +46,7 @@ export function getStackConfig(): StackConfig {
     rpcUrl: process.env.STACK_RPC_URL ?? DEFAULT_RPC_URL,
     webAppUrl: process.env.STACK_WEBAPP_URL ?? DEFAULT_WEBAPP_URL,
     graphqlUrl: process.env.STACK_GRAPHQL_URL ?? DEFAULT_GRAPHQL_URL,
+    contracts: loadContractAddresses(),
   };
 }