feat: add observation layer and external context routing

[SayandB]

Closes #15
Task: T-005

Summary

• add normalized browser and OSINT observation adapters
• route observed context into agent prompts and persisted task state

Tracking

Milestone: M4 — Observation and autonomy. Owner: SayandB. AI review and CI checks run on this PR.

Validation and risk

• pytest -q (see current CI matrix)
• external content is context only; collection is bounded and does not execute observed code.

No independent reviewer is available among repository collaborators; maintainer review is still required.

[github-actions]

PR Reviewer Guide 🔍

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⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ No major issues detected

[SayandB]

Tracking update: linked to T-005 / issue #15, milestone M4, owner SayandB, and labeled enhancement plus review effort 2/5. AI review and CI checks are attached to this PR. Independent reviewer assignment is pending another repository collaborator.