Fix both pool-level and filesystem metric parsing bugs

1. Prevent filesystem _fs_ metrics from overwriting pool totals
2. Fix filesystem name extraction to properly parse boot/root names

This resolves both the pool total display (showing 0.1GB instead of 220GB)
and individual filesystem display (showing —% —GB/—GB).

Cargo.lock

@@ -279,7 +279,7 @@ checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cm-dashboard"
-version = "0.1.116"
+version = "0.1.117"
 dependencies = [
  "anyhow",
  "chrono",
@@ -301,7 +301,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-agent"
-version = "0.1.116"
+version = "0.1.117"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -324,7 +324,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-shared"
-version = "0.1.116"
+version = "0.1.117"
 dependencies = [
  "chrono",
  "serde",