Replace legacy /developer/ links with their final paths #2383

35 internal links in 15 .mdx files still point at /developer/... paths. Each one works today only through a redirect in docs.json, almost all of them /developer/<section>/:slug* wildcards (for example /developer/contractkit/:slug* to /build/tools/libraries-sdks/contractkit/:slug*). The bare /developer/bridges relies on an exact redirect to /build/tools/bridges/bridges; the wildcard alone would send it to a page that doesn't exist. Readers get an extra redirect hop, mint broken-links --check-redirects cannot flag them while a wildcard matches, and they break if a wildcard is narrowed or removed. Each link should point at the final page, which must exist and be listed in docs.json navigation.

Found with:

rg -n --glob '*.mdx' '\(/developer/'

Files (link count), on main at 7f5d9bb:

• build/tools/dev-environments/hardhat.mdx (4)
• build/tools/dev-environments/remix.mdx (4)
• build/tools/explorers/overview.mdx (5)
• build/tools/libraries-sdks/contractkit/contracts-wrappers-registry.mdx (1)
• build/tools/libraries-sdks/contractkit/data-encryption-key.mdx (1)
• build/tools/libraries-sdks/contractkit/index.mdx (3)
• build/tools/libraries-sdks/contractkit/migrating-to-contractkit-v1.mdx (2)
• build/tools/libraries-sdks/contractkit/migrating-to-contractkit-v2.mdx (1)
• build/tools/libraries-sdks/contractkit/migrating-to-viem.mdx (1)
• build/tools/libraries-sdks/contractkit/setup.mdx (1)
• build/tools/libraries-sdks/contractkit/usage.mdx (1)
• build/tools/oracles/index.mdx (5)
• build/tools/overview/index.mdx (3)
• contribute-to-celo/release-process/smart-contracts.mdx (2)
• learn/network/overview.mdx (1)

Link targets: /developer/contractkit/migrating-to-viem (7), /developer/verify/celoscan (3), /developer/verify/blockscout (3), /developer/indexers/overview (3), /developer/verify/remix (2), /developer/verify/hardhat (2), /developer/explorers/block-explorers (2), /developer/explorers/analytics (2), /developer/contractkit/contracts-wrappers-registry (2), and one each of /developer/oracles/wit-oracle/ (trailing slash), /developer/oracles/wit-oracle, /developer/oracles/redstone, /developer/oracles/quex-oracles, /developer/oracles/band-protocol, /developer/explorers/overview, /developer/contractkit/usage, /developer/contractkit/setup, /developer/bridges/bridges and /developer/bridges (bare).

Found while reviewing #2366, which fixed the one /developer/ link on build/tools/libraries-sdks/contractkit/odis.mdx. Part of #2266.