p2: digest with in-sift FIFO, SQLite caches, Honcho context, recover

Dixie is capped (max_inflight 2, queue_depth 8, queue_wait 20s) and
never queued on llama-server. Streaming chat, thinking off, 45s
fallback to clean. Digest and chunk-embedding caches are
content-addressed SQLite (Honcho context is not cached). Recover
uses the guarded Fetcher. guardian-star is refused in code.

vendor/modernc.org/libc/.gitignore

@@ -0,0 +1,7 @@
+*.gz
+*.zip
+go.work
+go.sum
+musl-*
+COPYRIGHT-MUSL
+.claude/