docs: update ISO docs for Aider+Pi harness completion and sync with main codebase

- Updated firstboot completion messages: Aider and Pi now listed as primary harnesses, Codex as optional
- Added [Unreleased] section to CHANGELOG documenting Aider venv provisioning and harness integration
- Reflects completion of Aider+Pi harness migration across clawdie-ai and clawdie-iso

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

CHANGELOG.md

@@ -5,6 +5,17 @@ For detailed release notes, see `RELEASE-NOTES-*.md` files.
 
 ---
 
+## [Unreleased]
+
+### Added
+- Aider+Pi harness venv provisioning — `firstboot/shell-deploy.sh` now creates `/opt/clawdie/venv/aider` with pinned deps: `aider-chat==0.86.2`, `litellm==1.81.10`, `tree_sitter==0.20.4`
+- Aider availability check in post-install verification (logs `aider` version at end of deployment)
+
+### Improvements
+- Updated firstboot completion messages to highlight Aider and Pi as primary harnesses (Codex listed as optional alternative)
+
+---
+
 ## [0.9.0] — 2026-04-06
 
 **Codename:** Unified Architecture

firstboot/firstboot.sh

@@ -288,5 +288,7 @@ run_step "npm-globals" clawdie_shell_npm_globals_install "Install bundled npm CL
 run_step "deploy"  clawdie_shell_deploy         "Extract tarball + npm install-all" 8
 
 log_msg "[firstboot] Complete."
-log_msg "[firstboot] Codex CLI (headless): codex login --device-auth"
-log_msg "[firstboot] Codex CLI (API key): printenv OPENAI_API_KEY | codex login --with-api-key"
+log_msg "[firstboot] Aider (primary harness): aider --help"
+log_msg "[firstboot] Pi (primary harness): pi --help"
+log_msg "[firstboot] Optional: Codex CLI (headless): codex login --device-auth"
+log_msg "[firstboot] Optional: Codex CLI (API key): printenv OPENAI_API_KEY | codex login --with-api-key"