Remove unused AgentScript model and constants

[mrostan]

What's new?

Removes the AgentScript / AgentScriptModule dataclasses and the
AGENT_SCRIPT_ENTRYPOINT / AGENT_SCRIPT_BUILTIN_MODULES constants.

These were only consumed by the agent script-execution feature, which is being
removed across apollo-agent and data-collector (flagged by customer
security reviews and confirmed unused by the team). Within agent-base these
symbols had no other references.

Related PRs

• apollo-agent — removes the /api/v1/agent/execute_script endpoint + RestrictedPython executor
• data-collector — removes the script-based query-execution subsystem that called it

Testing

• Existing unit tests pass (43 passed)

Merge ordering

Part of a 3-repo change. Safe to merge independently, but the coordinated dev
rollout is: agent-base + apollo-agent first, then bump data-collector's
mcd-agent/agent-base pin.

🤖 Generated with Claude Code

[santiagoaguiar]

Reviewed for completeness and blast radius — no findings, this is clean.

• The diff removes exactly AgentScriptModule, AgentScript, AGENT_SCRIPT_ENTRYPOINT, and AGENT_SCRIPT_BUILTIN_MODULES; a full-branch grep confirms zero remaining references. AgentScript was a standalone AgentOperation subclass — nothing in serde.py or the operation dispatch path special-cases it.
• Checked all agent-base consumers across the org (apollo-agent, agent-common, hermes-agent, sna-artemis-agent, and data-collector transitively via mcd-agent): only apollo-agent ever imported these symbols, and apollo-agent #315 removes those imports. The data-collector's AgentScript is its own local dataclass, removed by data-collector #2414. All consumers use exact version pins, so merging this breaks no one — the ordering note in the description is accurate.
• Only operational note: tag a release (v0.0.5) after merge so apollo-agent can bump its pin once #315 lands.