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

.opencode/commands/repl-block.md

@@ -2,12 +2,16 @@
 description: Send a lisp block from an org file to the REPL
 ---
 
-Extract a `#+begin_src lisp` block from an .org file and send it to the
-running daemon REPL.
+Extract a `#+begin_src lisp` block from an .org file and pipe it to the
+running daemon REPL. Identify the block by function name or index.
+
+The `--package` flag wraps the block in `(in-package ...)` so it evaluates
+in the right namespace — essential when the block references symbols from
+a specific package without the package prefix.
 
 Usage: /repl-block <file.org> --function <name>
-       /repl-block <file.org> --block <number>
        /repl-block <file.org> --function <name> --package <pkg>
+       /repl-block <file.org> --block <number>
 
-The --package flag wraps the block in an (in-package ...) form.
-Use --block to identify by 1-based index, --function to find by defun name.
+Example:
+  /repl-block projects/passepartout/org/channel-tui-view.org --function view-status --package :passepartout.channel-tui