fix repl-block, check-tangle, commands: READMEs, exit codes, path resolution

repl-block:
- Listing mode exits 0, not 1 (listing is not an error)
- Dead lines parameter removed from find_by_function
- Block listing goes to stderr (not stdout) so piped use works
- Added README.org

check-tangle:
- Fixed tangle tool resolution: prefer local projects/tangle-tool/tangle
- Fixed path resolution for relative and absolute tangle paths
- Removed 2>/dev/null suppression so tangle errors are visible
- Added README.org

Commands:
- Rewrote all three .opencode/commands/*.md with proper prompts

projects/repl-block/README.org

@@ -0,0 +1,28 @@
+#+TITLE: repl-block
+
+Extract a ~#+begin_src lisp~ block from an .org file and output it to stdout,
+ready to pipe to ~repl~ or inspect.
+
+== Usage
+
+#+begin_src shell
+  repl-block org/file.org --function foo | repl
+  repl-block org/file.org --block 3
+  repl-block org/file.org --function foo --package :my-package
+  repl-block org/file.org                  # list all blocks
+#+end_src
+
+== Identifying blocks
+
+By function name (--function): scans all blocks for (defun <name> ...) and
+outputs the containing block. By index (--block): 1-based position in file.
+
+The --package flag prepends an ~(in-package ...)~ form so the REPL evaluates
+in the right namespace.
+
+Combine with ~repl~ to send a block directly to the daemon:
+  repl-block org/channel-tui-view.org --function view-status --package :passepartout.channel-tui | repl
+
+== Requires
+
+Python 3. No dependencies.

projects/repl-block/repl-block

@@ -41,7 +41,7 @@ def extract_blocks(lines):
     return blocks
 
 
-def find_by_function(blocks, name, lines):
+def find_by_function(blocks, name):
     for line_no, body in blocks:
         for bline in body:
             if re.match(rf"\(def(un|macro|method|var|parameter|class|struct|package)\s+{re.escape(name)}\b", bline):
@@ -76,7 +76,7 @@ def main():
     blocks = extract_blocks(lines)
 
     if args.function:
-        line_no, body = find_by_function(blocks, args.function, lines)
+        line_no, body = find_by_function(blocks, args.function)
         if body is None:
             print(f"No block found containing function '{args.function}'", file=sys.stderr)
             return 1
@@ -86,12 +86,12 @@ def main():
             print(f"Block {args.block} not found (file has {len(blocks)} blocks)", file=sys.stderr)
             return 1
     else:
-        # Print listing
+        # Print listing to stderr so piping still works
         for idx, (line_no, body) in enumerate(blocks, 1):
             first = (body or [""])[0][:60]
-            print(f"  {idx}: line {line_no}: {first}")
+            print(f"  {idx}: line {line_no}: {first}", file=sys.stderr)
         print(f"\n{len(blocks)} total blocks", file=sys.stderr)
-        return 1
+        return 0
 
     if args.package:
         pkg = args.package