feat(aidd-qa): create an implementation-independent QA plugin

[blafourcade]

Problem

Functional QA currently lives in aidd-dev as Browser QA, while technical test creation also lives in aidd-dev. This keeps implementation work and independent acceptance validation under the same concern.

The framework has no installable aidd-qa plugin, despite the earlier proposal in #69 and the need for QA that validates observable behavior against acceptance criteria.

Scope

• Create an installable aidd-qa plugin.
• Define its concern as implementation-independent acceptance validation and reviewer evidence.
• Move Browser QA from aidd-dev into the new plugin.
• Preserve its sourced scenarios, deterministic setup, teardown, reports and video evidence.
• Give the plugin a QA entry point that consumes acceptance criteria and a reviewed candidate.
• Keep browser execution as its first supported interface.
• Register the plugin in the marketplace, release configuration and version manifest.
• Add the plugin to the architecture taxonomy and generated documentation.
• Keep it off the recommended installation path until its integration is proven.
• Define a compatibility path for the existing Browser QA invocation.

Acceptance criteria

• plugins/aidd-qa/ is independently installable.
• Its manifest, router, actions and assets satisfy the plugin architecture checks.
• QA scenarios derive from acceptance criteria rather than implementation details.
• Browser QA produces expected behavior, actual behavior, verdict and evidence per scenario.
• Browser scenarios retain validated video evidence.
• aidd-dev no longer owns functional Browser QA after migration.
• Existing Browser QA users receive a compatible transition or an explicit migration message.
• Marketplace, release and architecture checks include aidd-qa.
• The plugin is initially marked recommended: false.
• The plugin works in Claude Code and one additional supported host.

Prior art in this repo

• plugins/aidd-dev/skills/11-browser-qa/
• PR feat(framework): add QA and communication evaluations #512.
• feat: extract role plugins — pm, qa, architect #69, which proposed a QA plugin but did not create one.
• docs/CREATE_PLUGIN.md.

Out of scope

• Technical test generation.
• Code review.
• Application fixes.
• Automatic pull-request merge.
• Claiming API or CLI QA support before those interfaces have executable providers.

[blafourcade]

Shipped in #917, released as aidd-qa-v1.0.0 (#924). Follow-ups: #918, #919.