test sweep: cover daemon pql/git command exception branches (T-91)

Two fault-injection test files driving every pql.* and git.* daemon
handler with a Client whose toolchain points at a non-existent
binary. Each underlying Process.run throws ProcessException → wrapped
as PqlException / GitException → the handler's catch branch fires
and surfaces a toolError IpcResponse.

- pql_commands_errors_test (18 cases): every pql.* command lands in
  the catch + _pqlError helper.
- git_commands_errors_test (14 cases): every git.* command lands in
  the catch + _gitError helper. Skipped: stage-hunk + unstage-hunk
  which go through GitClient._applyPatch (uses Process.start, throws
  ProcessException directly without rewrapping in GitException).

Coverage: src/daemon/pql_commands.dart 105/149 -> 148/149 (99%);
src/daemon/git_commands.dart 122/146 -> 142/146 (97%).

Total coverage 91.59% -> 92.33%; floor bumped to 92.

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

pubspec.yaml

@@ -18,7 +18,7 @@ repository: https://github.com/postmeridiem/clide
 
 # Pre-push line-coverage floor. Ratchets up only — see D-66.
 # Reading: `awk -F: '/^coverage_floor:/ {gsub(/ /,"",$2); print $2}' pubspec.yaml`.
-coverage_floor: 91
+coverage_floor: 92
 
 # Project metadata (was project.yaml, folded in per D-056).
 # version: above is the single source of truth. The Makefile reads