fix: remove obsolete Pi directory migration

[kunchenguid]

Intent

Implement the captain-authorized post-PR-27 cleanup for public kunchenguid/dotfiles. Remove the obsolete Pi migration activation in home.nix completely, including its now-unused lib argument, while preserving the fresh declarative out-of-store whole-directory themes and extensions links, individual models.json and settings.json links, immutable package declarations, and Pi privacy/runtime ownership boundaries. Per captain follow-up, delete the dedicated migration/content-assertion test and all wiring rather than replacing it with another source-text test. Validate only the supported fresh declarative configuration using non-activating Nix evaluation/build commands; do not activate, switch, rebuild live configuration, or disturb the independent Calm work.

What Changed

• Remove the obsolete Pi directory migration activation hook and its unused lib argument from home.nix.
• Delete the dedicated Pi migration and source-content assertion test while retaining the declarative out-of-store links for Pi themes, extensions, and configuration files.

Risk Assessment

✅ Low: The change is narrowly scoped and fully matches the authorized cleanup while preserving all required declarative Pi links, immutable package pins, and runtime ownership boundaries.

Testing

Inspected the commit delta and deleted-test references, evaluated all four Pi links and package pins through the configuration, built the Home Manager activation package without activating it, and inspected the generated result; the fresh declarative setup works as intended, privacy boundaries remain intact, and the worktree stayed clean.

Evidence: Fresh declarative Pi configuration evidence

Shows four out-of-store Pi links, immutable package pins, absent migration activation, successful non-activating Home Manager build, and excluded private/runtime paths.

Fresh declarative Pi configuration - non-activating evaluation/build evidence

themes source wrapper: /nix/store/n434g2401s81f5ixlry2mvyrs8r4f0c0-hm_themes
themes out-of-store target: /Users/kunchen/.dotfiles/home/.pi/agent/themes
extensions source wrapper: /nix/store/jfaz69ah9p2lqf63fpykzkxm3xxngqq4-hm_extensions
extensions out-of-store target: /Users/kunchen/.dotfiles/home/.pi/agent/extensions
models.json source wrapper: /nix/store/idx9g0gyd8grwynchnr13pra2fy4yndq-hm_models.json
models.json out-of-store target: /Users/kunchen/.dotfiles/home/.pi/agent/models.json
settings.json source wrapper: /nix/store/al802c8shljb11yr802619y68b719zbv-hm_settings.json
settings.json out-of-store target: /Users/kunchen/.dotfiles/home/.pi/agent/settings.json

immutable Pi packages: ["npm:@ryan_nookpi/pi-extension-codex-fast-mode@0.2.6","git:github.com/algal/pi-openai-server-compaction@c6d593087709e9481223dc6c6c2269b371b5e055"]
migration activation declared: false

built activation package without activation: /nix/store/l716k9kh4z39ls29c8xhi7j4i2smkxkq-home-manager-generation
generated activation contains obsolete migration code: false
generated managed Pi paths:
extensions
models.json
settings.json
themes
generated runtime/private Pi paths: absent

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• git diff --unified=80 9123c4432e7bd0ace329bb9cef3d620f0045a452..7a0a99e3120128e15bb74224886072fc1fb3f646 -- home.nix flake.nix Makefile tests README.md
• rg -n "pi-home-manager|migratePiAuthoredDirectories|home-manager|darwinConfigurations|checks" .
• nix eval --raw '.#darwinConfigurations.mac.config.home-manager.users.kunchen.home.file.".pi/agent/<path>".source' for themes, extensions, models.json, and settings.json
• nix eval --json '.#darwinConfigurations.mac.config.home-manager.users.kunchen.home.activation' with migration-key inspection
• nix build --no-link --print-out-paths '.#darwinConfigurations.mac.config.home-manager.users.kunchen.home.activationPackage'
• Inspected the generated activation script and managed Pi tree for obsolete migration code, expected declarative paths, and excluded private/runtime paths
• git status --short after testing

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.