perf: parallel indexing, embedding cache, HNSW ANN, lazy imports

[hellodk]

Summary

Addresses 6 performance bottlenecks in the Champ VS Code extension codebase, plus a full review pass fixing 9 additional issues (race conditions, CSP violations, OOM risks).

Changes

Core optimizations (commit dccd00b)

• Parallel indexing — Promise.allSettled() with 6-concurrency limiter in indexing-service.ts
• Embedding content-hash cache — Map<sha256, Float32Array> + disk persistence in embedding-service.ts
• Tool result truncation 500→3000 — first/last preservation with truncateForMetrics() in tool-calling-loop.ts
• Parallel independent tool calls — Promise.allSettled() for read-only tools
• Lazy imports — dynamic import() for IndexingService, MultiAgentRunner, TeamMarketplaceClient in extension.ts
• HNSW ANN vector index — optional hnswlib-node with brute-force fallback for >10K entries in vector-store.ts
• Smart router dedup — 3 dedup passes→1 mergeModels() in smart-router.ts
• Response cache wired into ToolCallingLoop for team-agent flows

Review fixes (commit dd37293)

Issue	Severity	Fix
Fire-and-forget void this.saveIndex() / saveCache()	Critical	await Promise.allSettled() before return
Embedding cache unbounded growth (OOM)	High	LRU eviction at 10K entries
readFileSync blocks event loop in parallel workers	High	await fsp.readFile() + async readdir
HNSW label↔entry desync during async build	High	Version counter with stale-build retry
Function() constructor violates CSP	High	Standard import("hnswlib-node")
No dimension validation on disk cache load	Medium	Skip entries with mismatched vec.length
Rapid onChange orphans IndexingService	Medium	Generation counter
Binary cache format to avoid OOM on save	Medium	JSON header + raw Float32 bytes
Cache namespace collision (tool-loop/default)	Medium	Actual provider.name + config.model

Verification

• Typecheck: 0 errors
• Lint: 0 errors (10 pre-existing warnings)
• Tests: 1506 passed, 5 skipped

Checklist

• No readFileSync in async code paths
• No Function() constructor (CSP-safe)
• All saves awaited (no fire-and-forget)
• LRU eviction on unbounded caches
• Version counters on async index builds
• Generation counters on lazy instantiation