fix(914): thread-local ALL_OPS/VECTOR_CLOCK in cfg(test) so compaction tests don't race

Root cause was not the persist channel (the test-mode channel is unbounded
and its receiver is leaked, so sends never fail). It was that `ALL_OPS` and
`VECTOR_CLOCK` were process-wide `OnceLock` globals while `CRDT_STATE` was
already thread-local — so one test thread's `apply_compaction` would prune
another test thread's freshly-written ops out of the shared journal, and
the subsequent `all_ops_json()` read in `compaction_reduces_ops` would
return fewer than the 5 it had just written.

Mirror the pattern already used for `CRDT_STATE` and `SnapshotState`: in
`cfg(test)` use thread-local `OnceLock<Mutex<...>>`s for the op journal and
vector clock, accessed via new `all_ops_lock()` / `vector_clock_lock()`
helpers. Production code path is unchanged (still the global statics set
during `init()`).

Touches ops/read/snapshot call sites to go through the helpers. Note in
passing that this overlaps backlog story 518; that story is about the
production-side persist path, this is the cfg(test)-only journal-isolation
slice.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/crdt_state/read.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 
 use bft_json_crdt::json_crdt::*;
 
-use super::state::{ALL_OPS, apply_and_persist, get_crdt, rebuild_index};
+use super::state::{all_ops_lock, apply_and_persist, get_crdt, rebuild_index};
 use super::types::{PipelineDoc, PipelineItemCrdt, PipelineItemView};
 use bft_json_crdt::op::ROOT_ID;
 
@@ -55,8 +55,7 @@ pub struct CrdtStateDump {
 pub fn dump_crdt_state(story_id_filter: Option<&str>) -> CrdtStateDump {
     let in_memory_state_loaded = get_crdt().is_some();
 
-    let persisted_ops_count = ALL_OPS
-        .get()
+    let persisted_ops_count = all_ops_lock()
         .and_then(|m| m.lock().ok().map(|v| v.len()))
         .unwrap_or(0);