docs: reposition GeoTask as Task Context Engine

[stpku]

Why

GeoTask's public story still presented the project as a verifiable spatiotemporal world model / trusted world-state runtime, while the current public Core has already moved to task-relative context semantics.

This PR makes the public product surface match the current architecture and published implementation:

• GeoTask = Spatiotemporal Task Context Engine for AI Agents
• North Star = Task Sufficiency at Minimum Context Cost
• explicit separation of Relevance / Applicability / Resolution Adequacy / Sufficiency
• explicit boundary: GeoTask does not own world truth
• independent provider model: WorldState / GIS / API / Sensor / Database / other providers
• public Warehouse Robot Picking consumer as concrete cross-domain proof
• temporal reassessment / minimum rebuild as the dynamic context direction
• historical World-State / Verification assets remain available as compatibility history, not future semantic ownership

Public surface changed

• README.md
• README.en.md
• ROADMAP.md
• site/index.html
• site/en/index.html
• tests/test_project_portal.py

Compatibility decisions

• all GT01–GT42 public case routes remain discoverable from the Chinese portal;
• existing sitemap / nested case routes remain unchanged;
• historical docs and released artifacts are not deleted;
• no Core, provider, release, workflow, or production behavior is changed.

Verification intent

CI should prove that the new portal preserves static-site safety, public case routes, sitemap coverage, relative-link closure, public manifest expectations, and the updated positioning contract.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Make the advertised consumer runnable after installation

For users following the immediately preceding pip install geotask-core instructions, this example fails with ModuleNotFoundError: examples: MANIFEST.in prunes examples, and setuptools packages only geotask_core*. Either instruct users to clone/run from the repository, package the independent consumer, or demonstrate the same composition through imports available in the installed package.

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[chatgpt-codex-connector]

Restore the keyboard skip link

For keyboard-only users on the rebuilt Chinese portal, the previous focus-visible “跳到主要内容” link and its #main target have been removed while the sticky header still contains numerous focusable links. Every visit or return now requires tabbing through the entire header before reaching the page content; restore the skip link and an id on the main landmark.

Useful? React with 👍 / 👎.