Fix pip 26+ egg fragment syntax, add ARM build docs

- Fix unquoted $flag in install.bash (unary operator error when no arg)
- Fix pip install syntax: use PEP 440 direct URL format for CKAN and
  ckanext-scheming (pip 26+ rejects extras in #egg= fragment)
- Add CLAUDE.md with architecture notes, known issues, and sysadmin setup
- Add deployment-from-source section to README for ARM users

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -36,6 +36,44 @@ wget -O - https://github.com/dathere/ckan-devstaller/releases/download/0.2.0/ins
 wget -O - https://github.com/dathere/ckan-devstaller/releases/download/0.2.0/install.bash | bash
 ```
 
+## Deployment (build from source)
+
+Use this path when the release binary does not match your architecture (e.g. ARM / Apple Silicon).
+
+### Prerequisites
+
+- Ubuntu 22.04 (fresh instance)
+- Rust toolchain
+
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+source ~/.cargo/env
+```
+
+### Build and run
+
+```bash
+git clone https://github.com/dathere/ckan-devstaller.git
+cd ckan-devstaller
+cargo build --release
+./target/release/ckan-devstaller
+```
+
+Pass `--default` for non-interactive mode:
+
+```bash
+./target/release/ckan-devstaller --default
+```
+
+### Add a sysadmin after install
+
+```bash
+/usr/lib/ckan/default/bin/ckan -c /etc/ckan/default/ckan.ini user add <username> email=<email> password=<password>
+/usr/lib/ckan/default/bin/ckan -c /etc/ckan/default/ckan.ini sysadmin add <username>
+```
+
+CKAN will be available at `http://localhost:5000`.
+
 ## Demos
 
 ### Interactive customizable installation