build(deps): migrate all agents to a2a-sdk 1.0

[pdettori]

Summary

The a2a-sdk has released version 1.0, which is a breaking change from the 0.x series currently used across all A2A agents. Dependabot opened PRs for this upgrade (#258, #261, #268, #270) but they were closed because:

1. The a2a-sdk 1.0 release has significant API surface changes
2. All agents should be migrated together for consistency
3. The uv.lock files need regeneration (Dependabot doesn't do this)
4. Manual validation is required for each agent

Affected Agents

Agent	Current Constraint	Target
a2a/a2a_contact_extractor	>=0.2.5,<0.4.0	>=1.0.1
a2a/a2a_currency_converter	>=0.2.5,<0.4.0	>=1.0.1
a2a/file_organizer	>=0.3.26	>=1.0.1
a2a/image_service	>=0.2.16	>=1.0.1

Tasks

• Review a2a-sdk 1.0 changelog for breaking changes
• Update a2a_contact_extractor — adjust imports/API calls, regenerate lockfile
• Update a2a_currency_converter — adjust imports/API calls, regenerate lockfile
• Update file_organizer — adjust imports/API calls, regenerate lockfile
• Update image_service — adjust imports/API calls, regenerate lockfile
• Run test-startup locally to verify all agents start cleanly
• Create single bundled PR with all changes

Context

Closed Dependabot PRs: #258, #261, #268, #270

Assisted-By: Claude Code

[esnible]

A PR for another orgs agents can be seen at https://github.com/a2aproject/a2a-samples/pull/527/changes . We'll need to do the same thing.

[esnible]

Everyone please test image-service before I upgrade all of the other agents.

• @pdettori I needed to enable A2A 0.3 compatibility on image-service so that Kagenti could talk to it. Unless there are objections, I will create an Issue to upgrade Kagenti backend so that it can talk to A2A 1.x agents.
• Kagenti's A2A streaming UI AgentChat.tsx silently ignores error responses from agents. A version of image-service that only spoke A2A 1.x returned {"error":{"code":-32601,"message":"Method not found"},"id":"0acfb9c1-9a7d-4e31-ba4e-e4c6caace5b5","jsonrpc":"2.0"}. Because the agent didn't preface it with data:, Kagenti ignored that response. Shall I create an issue?