feat(tools): 10 new native performance/parallelism tools

batch_patch — Apply up to 10 edits atomically (transactional early-stop).
  Replaces N serial patch calls with one batch call.

parallel_shell — Run up to 8 shell commands concurrently with bounded
  goroutines. Each classified individually through the danger gate.
  Structured results with stdout, stderr, exit_code, duration_ms.

http_batch — Fetch up to 10 URLs in parallel goroutines. Returns status,
  content_length, error per URL. ClassifyURL gated per URL.

math_eval — Native arithmetic expression evaluator using go/parser + AST
  walk. Supports +, -, *, /, parentheses, decimals. Directly replaces
  bc/expr/python -c forks (hits quick_math benchmark).

diff — LCS-based structured diff between two files or file-vs-string.
  Returns typed hunks (equal/added/removed) with line-by-line data.
  Zero dependencies, no diff fork.

count_lines — Streaming line/byte/char counter for up to 20 files in
  parallel. Zero-alloc on content (bufio.Scanner). Replaces wc fork.

multi_grep — Search for up to 10 regex patterns in parallel, each with
  its own goroutine directory walk. Directly targets multi_search
  benchmark — replaces N serial search_files calls.

json_query — JSON path query engine using dot-path syntax with array
  indexing (key.sub[0].name). Go encoding/json decoder, no jq fork.

tree — Structured directory tree listing with file counts, sizes,
  nesting. Configurable depth and hidden-file filtering.

checksum — SHA-256/SHA-1/MD5 hashing using Go crypto stdlib. Up to
  10 files in parallel. Replaces sha256sum/md5sum forks.

Security: all tools gated through danger.ClassifyPath/ClassifyURL +
  CheckOperation. All file opens use O_NOFOLLOW. All registered in
  classifyToolCall() for batch approval gate. 25 new tests.
  0 new dependencies.

Author: molty3000

cmd/odek/main.go

@@ -1400,6 +1400,16 @@ func builtinTools(dc danger.DangerousConfig, sm *skills.SkillManager, approver d
 		&batchReadTool{dangerousConfig: dc},
 		&globTool{dangerousConfig: dc},
 		&fileInfoTool{dangerousConfig: dc},
+		&batchPatchTool{dangerousConfig: dc},
+		&parallelShellTool{dangerousConfig: dc, approver: approver},
+		newHTTPBatchTool(dc),
+		&mathEvalTool{},
+		&diffTool{dangerousConfig: dc},
+		&countLinesTool{dangerousConfig: dc},
+		&multiGrepTool{dangerousConfig: dc},
+		&jsonQueryTool{dangerousConfig: dc},
+		&treeTool{dangerousConfig: dc},
+		&checksumTool{dangerousConfig: dc},
 		newBrowserTool(dc),
 	}