fix(docs): correct SDK creation and unavailable explorer links

[drewstone]

The Sandbox quickstart's first create call used image, which the current SDK rejects. Both quickstart examples and the SDK reference now use environment, with the accepted environment values explained beside the reference example.

The endpoint gate also found that explorer.tangle.tools no longer resolves. Base Mainnet guidance now links to BaseScan. The older token table retains its addresses as text instead of linking them to the unavailable explorer or misidentifying them as Base addresses; its per-chain explorer links remain intact.

Validation: all three extracted create option objects typecheck against published @tangle-network/sandbox@0.39.0; a negative image case is rejected. Changed-file formatting, harness-copy, and live endpoint checks pass (238 URLs). The final documentation rebuild and all CI checks pass. The Netlify preview renders all three creation examples with environment and none with image. An independent agent reviewed the four-file change without findings.

[netlify]

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[tangletools]

Independent code review completed for 08e7802 by the separate Legal adoption reviewer. No blockers in the four-file diff. The published Sandbox SDK contract supports environment for named environments, container references, and built image IDs. NetworkResources already identifies Base Mainnet chain 8453, so BaseScan matches the documented chain. The multichain token table preserves addresses without incorrectly remapping them to Base. Validation evidence supplied by the implementation owner: all three extracted create examples typecheck against Sandbox 0.39.0 with a rejected legacy image case; final documentation build and all CI checks pass; Netlify preview contains all three corrected examples. The independent review did not rerun CI or a browser. This approval records that specific completed review; it is not an automatic or blanket approval.