Render configuration-cache status in the caching Job Summary (#989)

Render the configuration-cache restore-state in the caching Job Summary,
driven by the new `CacheReport.configurationCache` field produced by the
`gradle-actions-caching` provider.

## What's here

- `cache-service.ts`: add a `ConfigurationCacheStatus` type
(`not-active` / `restored` / `not-restored` / `restore-incomplete`) and
an optional `configurationCache` field on `CacheReport`.
- `caching-report.ts`: a `CONFIG_CACHE_COPY` map and a prominent status
line in `renderCachingReport`, beside the cleanup line. The `not-active`
case links to the `#cache-encryption-key` docs.

## Cross-repo dependency

The field is populated by gradle/actions-caching PR #75 ("Restore
configuration-cache support for simple builds"). This rendering compiles
independently (it uses this repo's own `CacheReport` type) and renders
nothing until the vendored `gradle-actions-caching` bundle is refreshed
from that branch — so this should land with/after the vendor refresh.

## Verification

`npm run check` clean; full Jest suite (366 tests) passes, including 3
new rendering tests.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

sources/src/cache-service.ts

@@ -27,6 +27,8 @@ export type CacheCleanupStatus =
     | 'disabled-config-cache-hit'
     | 'disabled-readonly'
 
+export type ConfigurationCacheStatus = 'not-active' | 'restored' | 'not-restored' | 'restore-incomplete'
+
 export interface CacheEntryReport {
     entryName: string
     requestedKey?: string
@@ -47,6 +49,7 @@ export interface CacheEntryReport {
 export interface CacheReport {
     status: CacheStatus
     cleanup?: CacheCleanupStatus
+    configurationCache?: ConfigurationCacheStatus
     entries: CacheEntryReport[]
 }