docs: expand learning-resources.mdx with curated tutorials per 'Coming Soon' section. Addresses community demand for practical guides. Links to agents, Base Account, etc.

[parado451]

What changed? Why?

• Fits existing structure: No new top-level sections. The get-started/learning-resources page already exists and has a "Coming Soon" placeholder for updated tutorials, community-contributed resources, etc. This is a natural fit under Resources / Quickstart/Guides concepts.

• Addresses real gaps: Docs emphasize AI-friendly, runnable content and cross-links. Community feedback and "Coming Soon" notes show demand for more practical learning paths (e.g., agents, smart accounts, mini-apps, tokens). Recent commits show active updates around agents, Builder Codes, notifications, etc., but learning resources lag.

• Small, focused PR: One page update with links, short descriptions, and verification notes. Prioritizes happy path + cross-links.

Notes to reviewers

• Consistent terminology (e.g., Base Account, OnchainKit, Agents).

• AI-friendly: Explicit tool names, direct links, copy-paste friendly notes.

• No new subsections proliferation; use lists/Tabs if needed.

• Validates examples by selecting runnable/official ones.

[cb-heimdall]

🟡 Heimdall Review Status

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Reviews	🟡 0/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2