fix(worker): dedupe artifact boot replay, incremental route trie

[07prajwal2000]

Summary

• Fixes P1: artifact boot loads twice; every update rebuilds the whole route trie #191 — artifact boot replayed the initial snapshot twice, and every artifact update rebuilt the entire route trie from scratch.
• watchArtifacts/watchProjectArtifacts now use a single NATS KV watch (includeExisting toggles LastValue vs UpdatesOnly) instead of a separate loadProjectArtifacts() snapshot read followed by a watch — no more double replay of the initial state.
• compiledWorker.ts awaits the watch's initial replay before spawning the execution process, so it boots with a deduped snapshot exactly once.
• HttpRouteParser gained upsertRoute/removeRoute for incremental trie insert/prune; compiledRuntime.ts uses these per-artifact instead of rebuildRoutes() on every update.
• Removed listArtifacts() (natsKv.ts) — dead code left over from the old snapshot-read path, no remaining callers.

Test plan

• bun test packages/lib/tests/parser.spec.ts — 4/4 pass, covers upsert/remove without disturbing unrelated routes
• bun run --cwd apps/server lint (tsgo --noEmit) — clean
• Manually traced trie prune logic for shared-prefix routes (e.g. /api/users + /api/users/:id) and shared-method branches — correct, only prunes branches left with no children
• Verified KvWatchInclude.UpdatesOnly / LastValue against the installed nats package's type defs

🤖 Generated with Claude Code