feat: complete with-watch command inference

crates/with-watch/README.md

@@ -13,6 +13,15 @@ brew install delinoio/tap/with-watch
 
 ```sh
 with-watch cp src.txt dest.txt
+with-watch ls -l
 with-watch --shell 'cat src.txt | grep hello'
+with-watch sed -i.bak -e 's/old/new/' config.txt
 with-watch exec --input 'src/**/*.rs' -- cargo test -p with-watch
 ```
+
+## Inference Model
+
+- Passthrough and shell modes use built-in command adapters before falling back to conservative path heuristics.
+- Known outputs, inline scripts, patterns, and shell output redirects are filtered out of the watch set.
+- Pathless defaults are intentionally narrow: only `ls`, `dir`, `vdir`, `du`, and `find` implicitly watch the current directory.
+- `exec --input` remains the explicit escape hatch when a delegated command has no meaningful filesystem inputs or when fallback inference would be ambiguous.