feat(cli): add dailybot uninstall command with install-method detection

[xergioalex]

Summary

• One command to uninstall the CLI cleanly, mirroring the UX of dailybot upgrade. Auto-detects how the CLI was installed and runs the matching uninstall (pipx / uv tool / pip) or prints the right command for installs we don't own (brew uninstall, rm <binary>, editable dev install).
• Conservative-by-default: prompts for confirmation (-y / --yes to skip), supports --dry-run to preview, and keeps ~/.config/dailybot/ unless --purge is passed — so reinstalling later doesn't force a re-login.

Why this shape

Best-practice notes that drove the design (see docs/CLI_COMMAND_BEST_PRACTICES.md):

• Confirmation by default — uninstall is destructive; the prompt defaults to "no" so an accidental Enter is safe.
• --purge is opt-in — losing credentials and agent profiles silently is the kind of thing users only notice an hour later. Opt-in beats opt-out.
• Editable installs bail out early — same stance upgrade already takes; we don't want to pip uninstall someone's working clone out from under them.
• Manual hint for homebrew / binary — invoking brew uninstall or rm-ing our own running binary from inside the CLI is a recipe for sudo prompts, file locks, and "the binary disappeared while it was executing" weirdness on macOS/Windows.
• Subprocess via argv lists, never shell=True — same pattern as upgrade.

Change log

• dailybot_cli/install_method.py (new) — extracts _detect_install_method, _resolve_install_path, and the method-label table from commands/upgrade.py. Both upgrade and uninstall import from here so they can never disagree on what they call each install method or where it lives. Pure refactor of upgrade — its 12 existing tests pass unchanged.
• dailybot_cli/commands/uninstall.py (new) — follows the five-step CLI pattern: print plan, honor --dry-run, confirm (default no), execute or print manual command, optionally purge config.
• dailybot_cli/main.py — registers the new top-level command.
• tests/uninstall_test.py (new) — 20 tests covering: confirmation flow (decline / --yes / -y / safe default), every install-method dispatch, --dry-run (shouldn't even prompt), --purge (with and without an existing config dir, including the homebrew case where we delegate the package-manager work but still wipe config), subprocess failure exit-code propagation, missing-executable fallback, and top-level help integration.
• README — new "Uninstall" subsection right next to upgrade.
• AGENTS.md — project structure updated to mention the two new files.

Test plan

• ruff check dailybot_cli tests clean
• ruff format --check dailybot_cli tests clean
• mypy dailybot_cli clean
• pytest -x — 192 passed (172 existing + 20 new)
• Smoke-tested dailybot uninstall --help — example block renders cleanly
• Smoke-tested dailybot uninstall --dry-run in this editable install — correctly bails out with the editable-refusal message
• CI matrix (Py 3.10 + 3.12) green on this PR

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