feat(preprod): Add Size Analysis detector

[chromy]

Add PreprodSizeAnalysisGroupType (type_id=11003) with detector handler
and validators that integrate with the workflow engine to emit issues
when build size thresholds are exceeded.

• PreprodSizeAnalysisDetectorHandler: evaluates DataPackets from size
  comparisons and produces IssueOccurrences
• PreprodSizeAnalysisDetectorValidato validate detector creation via the API
• Register the GroupType import in preprod/grouptype.py

PRs:

• feat(preprod): Add Size Analysis detector #108208 Add size_analysis detector (this PR)
• feat(preprod): Hook size analysis detector to diff #108209 Hook size analysis detector to diff
• feat(preprod): Add new issue type to frontend #108210 Add new issue type to frontend
• feat(preprod): Add size monitor UI #108211 Add size monitor UI

Design doc

[github-actions]

This PR has a migration; here is the generated SQL for src/sentry/preprod/migrations/0027_size_analysis_subscription.py

for 0027_size_analysis_subscription in preprod

--
-- Create model SizeAnalysisSubscription
--
CREATE TABLE "sentry_sizeanalysissubscription" ("id" bigint NOT NULL PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY, "date_updated" timestamp with time zone NOT NULL, "date_added" timestamp with time zone NOT NULL, "project_id" bigint NOT NULL);
ALTER TABLE "sentry_sizeanalysissubscription" ADD CONSTRAINT "sentry_sizeanalysiss_project_id_41e3355e_fk_sentry_pr" FOREIGN KEY ("project_id") REFERENCES "sentry_project" ("id") DEFERRABLE INITIALLY DEFERRED NOT VALID;
ALTER TABLE "sentry_sizeanalysissubscription" VALIDATE CONSTRAINT "sentry_sizeanalysiss_project_id_41e3355e_fk_sentry_pr";
CREATE INDEX CONCURRENTLY "sentry_sizeanalysissubscription_project_id_41e3355e" ON "sentry_sizeanalysissubscription" ("project_id");

[sentry]

Bug: The extract_value method can cause a ZeroDivisionError when calculating a relative_diff because it divides by base without checking if base is zero.
_{Severity: MEDIUM}

Suggested Fix

Before performing the division in extract_value, check if base is 0. If it is, return a sensible default value, similar to the pattern used in src/sentry/preprod/vcs/status_checks/size/tasks.py which returns False in this scenario.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: src/sentry/preprod/size_analysis/grouptype.py#L127

Potential issue: In `PreprodSizeAnalysisDetectorHandler.extract_value()`, when
`threshold_type` is `"relative_diff"`, the code calculates a value by dividing by
`base`. However, the `_extract_base()` method does not prevent `base` from being `0`. If
a data packet results in a base size of 0, this will cause an unhandled
`ZeroDivisionError`, crashing the detector handler during evaluation. Similar code
elsewhere in the project explicitly checks for a zero base value, indicating this is a
known edge case that should be handled.