fix: commit docs canister ID mapping and tighten gitignore (#442)

- Only ignore .icp/cache (not all of .icp/) so canister ID mappings
  can be committed as intended for icp projects
- Remove outdated .icpdata ignore entry (no longer used)
- Ignore examples/*/.icp/ since this repo does not track canister IDs
  for the examples (neither local nor mainnet deployments)
- Commit docs-site/.icp/data/mappings/ic.ids.json (canister ID for docs)
- Restore cp in workflow (file is now in source control)

Author: marc0olo

.gitignore

@@ -2,13 +2,11 @@
 .DS_Store
 .cursor
 
-# Local (directories)
-.icp
+# icp-cli internal cache directory
+.icp/cache
 
-# This directory contains canister ID mappings which are encouraged
-# to be included in source control of icp canister projects.
-# They are ignored here because we are developing icp-cli itself.
-.icpdata
+# icp-cli state in examples (not source-controlled in this repo)
+examples/*/.icp/
 
 # often-used binaries
 pocket-ic

docs-site/.icp/data/mappings/ic.ids.json

@@ -0,0 +1,3 @@
+{
+  "docs": "ak73b-maaaa-aaaad-qlbgq-cai"
+}