Remove ec2 extra

I propose removing the few dependencies required by the ec2 extra. Here's an autogenerated scoping:

Current state

• In this branch, ec2 currently includes numpy and pandas only (no tqdm).pyproject.toml:99-102
• EC2 code is coupled to pandas in dallinger/command_line/lib/ec2.py via DataFrame, concat, merge, query, groupby, to_numeric, and to_markdown.ec2.py:13 ec2.py:138 ec2.py:164-169 ec2.py:220 ec2.py:250-287 ec2.py:301-304 ec2.py:855-856 ec2.py:985-1015
• EC2 tests also assume DataFrame return types and APIs (columns, iloc, etc.).test_ec2.py:4 test_ec2.py:42-44 test_ec2.py:90-107
• EC2 CLI registration is currently guarded by optional import + “install ec2 extra” messaging.__init__.py:126-134

Proposed refactor scope

1. Replace DataFrame-based EC2 internals with plain Python (list[dict] + small helper functions):

   • filtering by state/pem
   • selecting one instance by name/dns
   • grouping and joining instance pricing details
   • cost and uptime formatting/sorting
     (all currently done by pandas ops).ec2.py:250-287 ec2.py:301-304 ec2.py:985-1015

2. Replace DataFrame to_markdown() output with Rich table rendering (render_rich_table) so EC2 has no extra tabular dependency.ec2.py:138 ec2.py:304 ec2.py:352 ec2.py:369 utils.py:68-123

3. Update EC2 tests to assert behavior/output semantics on plain objects rather than DataFrame API specifics.test_ec2.py:42-44 test_ec2.py:90-107

4. Packaging cleanup:

   • remove numpy/pandas from [project.optional-dependencies].ec2
   • decide whether to keep an empty ec2 extra as a compatibility alias or remove it entirely
   • optionally remove ec2 from dev install aggregates if no longer needed.pyproject.toml:99-102 dev-requirements.in:1 constraints.in:1

Effort and risk

• Effort: small-to-medium (~0.5–1 day including tests).
• Main risk: preserving exact filtering/sorting/formatting behavior currently provided by pandas (especially cost computation and missing-value handling).ec2.py:279-291
• API compatibility risk: low for CLI users, moderate for external code importing EC2 helper functions and expecting DataFrames.

Optional follow-up refactors

• Once EC2 has no optional deps, remove the EC2 import guard and always register the command in CLI bootstrap.__init__.py:126-134
• Replace string-based query logic with explicit Python predicates to avoid quoting/escaping edge cases in instance names/DNS values.ec2.py:985-991

Start with the EC2 implementation in dallinger/command_line/lib/ec2.py and its tests in test_ec2.py, then inspect pyproject.toml, init.py, utils.py, dev-requirements.in, and constraints.in. Run the EC2 tests before changing behavior. Done means EC2 filtering, selection, pricing, formatting, CLI registration, tests, and dependency configuration work without the pandas or numpy extra.