fix: add missing createdOnPlatform for security-agent and app-builder

[pedroheyerdahl]

Follow-up to #307 (microdollar feature tracking).

Problem

Two code paths were spawning cloud-agent sessions without passing createdOnPlatform, causing their LLM usage to be attributed as cloud-agent instead of the correct feature.

Changes

Security Agent sandbox analysis (src/lib/security-agent/services/analysis-service.ts)

• Added createdOnPlatform: 'security-agent' to the initiateSessionStream call
• Extended existing test to assert the field is passed

App Builder legacy session backfill (src/lib/app-builder/app-builder-service.ts)

• Added createdOnPlatform: 'app-builder' to the prepareLegacySession call

Plan docs (plans/microdollar-feature-tracking.md)

• Rewrote implementation steps to reflect actual state
• Added remaining work items (CLI release + version bump needed)

Testing

• pnpm typecheck passes
• pnpm test -- src/lib/security-agent/services/analysis-service.test.ts passes (asserts createdOnPlatform: 'security-agent' in the mock call)

[kiloconnect]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Overview

This PR adds missing createdOnPlatform fields to two call sites and updates the feature-tracking plan document to reflect the current implementation state.

Code changes:

• app-builder-service.ts: Adds createdOnPlatform: 'app-builder' to the prepareLegacySession call in prepareLegacySession(). This was already present in the other two app-builder call sites (lines 121, 515) but was missing from this one — a clear oversight now fixed.
• analysis-service.ts: Adds createdOnPlatform: 'security-agent' to the initiateSessionStream call in startSecurityAnalysis(), ensuring security agent sandbox sessions are properly attributed.
• analysis-service.test.ts: Adds a corresponding test assertion for the new createdOnPlatform field.

Documentation: The plan document (plans/microdollar-feature-tracking.md) is updated to reflect the current state of implementation, replacing speculative steps with descriptions of what's actually been built and noting remaining work items.

Files Reviewed (4 files)

• plans/microdollar-feature-tracking.md - documentation update
• src/lib/app-builder/app-builder-service.ts - 0 issues
• src/lib/security-agent/services/analysis-service.ts - 0 issues
• src/lib/security-agent/services/analysis-service.test.ts - 0 issues