Normalize Avalanche explorer offer references

[jaasieldelgado131]

Summary

• Moved Avalanche explorer metadata for avalanche-explorer and avascan into canonical rows in references/offers/explorers.csv.
• Updated the Avalanche mainnet/testnet explorer listings to use explicit !offer: references.
• Kept the Avascan testnet listing's testnet-specific explore URL on the listing row while sharing reusable explorer metadata from the reference row.

Validation

• Parsed both changed CSV files with Python's csv module.
• Confirmed both changed files have consistent column counts.
• Confirmed avalanche-explorer and avascan are unique in references/offers/explorers.csv.
• Confirmed all Avalanche explorer !offer: references resolve to existing explorer offer slugs.
• Ran git diff --check.

Related to #1955.

Rewards address: 0xb43d90BB4E22A43D77e9bfbc2f1CA826ec1CaBF1

[github-actions]

Summary

Status	Count
🔍 Total	4
✅ Successful	4
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	0
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Full Github Actions output

[USS-Supervisor]

Verdict: APPROVE
Risk: LOW
Summary: The Avalanche explorer normalization is clean. The new avalanche-explorer and avascan canonical offer rows resolve from the listing refs, the Avascan testnet listing keeps its testnet-specific URL override, required validation passed, and the current review-cycle link-check passed after toggling check-links.
Findings: None.
Confidence: HIGH

[USS-Supervisor]

Hi @eugene17kotov - this stale PR looks ready for reviewer action: required CI is passing and I do not see a current creator-side blocker. I requested your review so it can keep moving. Could you please take a look when you have a chance?

[USS-Supervisor]

Hi @eugene17kotov, this stale PR is still waiting on reviewer action. Required checks are passing and I don't see a blocking review; could you please take another look when you can?

[USS-Supervisor]

Hi @eugene17kotov - friendly follow-up on this stale PR. Required CI is passing and I do not see a current creator-side blocker, so it is still waiting on reviewer action. Could you please take a look when you have a chance?

[USS-Supervisor]

Hi @eugene17kotov - friendly follow-up on this stale PR. Required CI is passing and I do not see a current creator-side blocker, so it is still waiting on reviewer action. Could you please take a look when you have a chance?

[USS-Supervisor]

Hi @eugene17kotov - friendly follow-up on this stale PR. Required CI is passing and I do not see a current creator-side blocker, so it is still waiting on reviewer action. Could you please take a look when you have a chance?

[github-actions]

Summary

Status	Count
🔍 Total	18
🔗 Unique	15
✅ Successful	18
⏳ Timeouts	0
🔀 Redirected	1
👻 Excluded	0
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Full Github Actions output

[github-actions]

Summary

Status	Count
🔍 Total	18
🔗 Unique	15
✅ Successful	18
⏳ Timeouts	0
🔀 Redirected	1
👻 Excluded	0
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Full Github Actions output

[USS-Supervisor]

Verdict: APPROVE
Risk: LOW
Summary: Re-reviewed current head e1cf5d21d07d6669431252b1b9d6ba36d4343df6 after the previous USS Supervisor approval was dismissed. The diff is narrow to Avalanche explorer normalization plus provider/offer metadata updates. Structured CSV checks passed for references/providers/providers.csv, references/offers/explorers.csv, and listings/specific-networks/avalanche/explorers.csv: stable column counts, no duplicate slugs, resolving !offer:avalanche-explorer / !offer:avascan, and existing mainnet.png / testnet.png chain logos. Source spot checks support the Avalanche Explorer and Avascan explorer/API metadata, including Avascan's Etherscan-compatible verification endpoint; the Avascan support bot page identifies itself as Avascan support. Required validation is green, and I refreshed check-links for this review cycle: run 30003029286 completed successfully on the current head with the bot summary showing 18/18 successful links and 0 errors/timeouts. check-links was removed before review submission.
Findings: None.
Confidence: HIGH