Fix local chezmoi bootstrap for global agent installs

[DanielZ818]

Summary / Why This Matters

This branch adds a reusable global/local agent-surface installer for Codex and then fixes the first-run bootstrap bugs that showed up on a non-owner machine.

Before the follow-up fixes, the installer could leave local setup half-working:

• chezmoi could be installed but not initialized
• first-run chezmoi apply could fail on missing template data like gui
• rendered chezmoi config could still point at the repo owner's ~/linux-config
• the current shell might not see ~/.local/bin, so a freshly installed chezmoi was not callable

This PR makes the bootstrap path work for a local clone under a different home-directory layout.

What Changed

• add scripts/executable_install-agent-surface to bootstrap:
  • repo-local AGENTS.md / AGENTS.repo.md / plans/
  • local .agents/skills/ or chezmoi-style dot_agents/skills/
  • global ~/.codex/AGENTS.md
  • global ~/.agents/AGENTS.md, ~/.agents/skills/, and ~/.agents/system-design/
• add fish completions for install-agent-surface
• add bash fallback ~/scripts path support in dot_bashrc
• make global installer bootstrap chezmoi when missing
• make global installer render a default ~/.config/chezmoi/chezmoi.toml when missing
• make global installer initialize ~/.local/share/chezmoi from the current repo when missing
• make .chezmoiignore tolerate missing first-run gui data
• render chezmoi sourceDir from the actual local clone path instead of hardcoding ~/linux-config
• update README, smoke-test coverage, installer plan notes, and lessons to reflect the new operator flow

How To Smoke Test

Use a fresh shell where ~/.local/bin is available, or add it first:

export PATH="$HOME/.local/bin:$PATH"

Run the global installer from this repo:

./scripts/executable_install-agent-surface --global --all-skills

Verify the global surfaces exist:

ls ~/.codex/AGENTS.md
ls ~/.agents/AGENTS.md
ls ~/.agents/skills
ls ~/.agents/system-design

Verify chezmoi is available and initialized:

command -v chezmoi
ls ~/.config/chezmoi/chezmoi.toml
ls ~/.local/share/chezmoi
chezmoi apply

Verify repo-local install modes still work:

./scripts/executable_install-agent-surface --target /tmp/test-agent-repo --skill commit-plan
./scripts/executable_install-agent-surface --target /tmp/test-agent-dotfiles --chezmoi --skill openai-docs

For fish-specific behavior, open a new fish shell and verify:

complete -C "install-agent-surface --"
command -v chezmoi

Tests Written / Verification Run

Automated tests written or updated:

• tests/scripts/executable_install-agent-surface_test.sh

Commands run:

• tests/scripts/executable_install-agent-surface_test.sh
• bash -n scripts/executable_install-agent-surface tests/scripts/executable_install-agent-surface_test.sh
• fish -n dot_config/fish/completions/install-agent-surface.fish
• ./scripts/executable_readme-recruiter-sync .
• chezmoi execute-template < .chezmoiignore

Commands not run:

• refresh-config
• a full real-machine chezmoi apply after the final sourceDir/template fixes from this branch

Known failing suites or unrelated failures:

• Not available from this branch work
• Git pushes to upstream origin fail from this environment with GitHub 403 for account DanielZ818

Follow-Up / Next Steps

• Merge this PR and verify the flow on a clean non-owner machine
• Consider a broader portability pass for the other historical ~/linux-config and /home/kevin/linux-config references that are outside this installer/bootstrap path

Reviewer Focus / What To Look For

Please focus on bootstrap safety and portability:

• whether the installer now covers the full first-run chezmoi path instead of only the binary install
• whether rendering sourceDir from the actual clone path is the right long-term behavior
• whether the global-vs-local install modes are clearly separated and low-risk for an existing machine
• whether the fish/bash path handling is sufficient for new sessions without surprising existing shell behavior

Risks, Caveats, Known Failures, And Rollback

• This PR changes bootstrap behavior for global installer runs, so the main risk is affecting first-run setup on machines that were previously relying on manual chezmoi init steps
• The installer intentionally leaves existing chezmoi config and source directories unchanged when they already exist, which reduces overwrite risk but means it will not repair arbitrary pre-existing local drift
• The repo still contains other hardcoded linux-config paths outside the installer/bootstrap path; those are not addressed here
• Rollback is straightforward:
  • remove the installer script and shell completion
  • revert the chezmoi template/ignore changes
  • revert the README and smoke-test updates
  • restore the previous shell path handling

UI Screenshots / Live Links

Not applicable for this shell/bootstrap workflow.