Rename content_hash to cid in CLI

Update CLI argument names and help text:
- Change argument names from content_hash to cid
- Update user-facing messages to use CID terminology
- Update README examples with CID syntax

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -75,8 +75,8 @@ export ARTDAG_L2=https://artdag.rose-ash.com
 # Using asset name
 ./artdag.py run dog cat
 
-# Using content hash
-./artdag.py run dog 33268b6e167deaf018cc538de12dbe562612b33e89a749391cef855b320a269b
+# Using CID
+./artdag.py run dog Qm33268b6e167deaf018cc538de12dbe562612b33e
 
 # Wait for completion
 ./artdag.py run dog cat --wait
@@ -112,13 +112,13 @@ export ARTDAG_L2=https://artdag.rose-ash.com
 ### View/Download Cached Content
 ```bash
 # Show info
-./artdag.py view <content-hash>
+./artdag.py view <cid>
 
 # Download to file
-./artdag.py view <content-hash> -o output.mkv
+./artdag.py view <cid> -o output.mkv
 
 # Pipe to mpv (use -o - for stdout)
-./artdag.py view <content-hash> -o - | mpv -
+./artdag.py view <cid> -o - | mpv -
 ```
 
 ### Import Local File to Cache
@@ -128,10 +128,10 @@ export ARTDAG_L2=https://artdag.rose-ash.com
 
 ### Delete Cached Content
 ```bash
-./artdag.py delete-cache <content-hash>
+./artdag.py delete-cache <cid>
 
 # Skip confirmation
-./artdag.py delete-cache <content-hash> -f
+./artdag.py delete-cache <cid> -f
 ```
 
 Note: Items that are inputs/outputs of runs, or published to L2, cannot be deleted.
@@ -151,7 +151,7 @@ Configs are reusable DAG definitions with fixed and variable inputs.
 ./artdag.py config <config-id>
 
 # Run a config with variable inputs
-./artdag.py run-config <config-id> -i node_id:content_hash --wait
+./artdag.py run-config <config-id> -i node_id:cid --wait
 
 # Delete a config
 ./artdag.py delete-config <config-id>
@@ -173,5 +173,5 @@ Configs are reusable DAG definitions with fixed and variable inputs.
 ./artdag.py runs
 
 # Download the output
-./artdag.py view <output-hash> -o result.mkv
+./artdag.py view <output-cid> -o result.mkv
 ```