fix: update typer to >=0.12.4 for PEP 604 union type support

[christian-byrne]

Fixes #355

PR #349 changed Optional[bool] type hints to bool | None syntax, but typer < 0.12.4 does not support PEP 604 union types, causing RuntimeError: Type not yet supported: bool | None.

Changes:

• Update typer dependency from >=0.9 to >=0.12.4 (adds PEP 604 support via typer#548)
• Remove deprecated is_flag parameter from typer.Option() calls (deprecated in typer 0.15.0, never worked properly)

Testing:

• All unit tests pass
• CLI works with typer 0.12.4 (minimum) and 0.21.1 (latest)
• No breaking changes - existing click<=8.1.8 pin is compatible with typer 0.12.4+

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #356      +/-   ##
==========================================
- Coverage   51.93%   51.81%   -0.13%     
==========================================
  Files          32       32              
  Lines        3489     3563      +74     
==========================================
+ Hits         1812     1846      +34     
- Misses       1677     1717      +40     

Files with missing lines	Coverage Δ
comfy_cli/cmdline.py	49.39% <ø> (ø)
comfy_cli/command/custom_nodes/command.py	43.19% <ø> (ø)

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[christian-byrne]

The failing CI checks are unrelated to this PR's changes - they are e2e test failures caused by network timeouts downloading PyTorch from download.pytorch.org:

WARNING: Connection timed out while downloading.
× Download failed after 6 attempts because not enough bytes were received (5.2 MB/188.8 MB)
╰─> URL: https://download.pytorch.org/whl/cpu/torch-2.10.0+cpu-cp310-cp310-linux_x86_64.whl
note: This is an issue with network connectivity, not pip.

These are known flaky tests - the main branch also had the same failures on PR #351 ("Fix ComfyUI repo URLs").

The core unit tests (Run pytest) and code checks (ruff_check, build) all pass successfully.

Re-running the failed jobs...