docs 2.0 (phase I)

[ryanwaits]

What does this PR do?

docs 2.0 (phase I)

the goal of phase I is to ship the revamped information architecture and navigation for docs 2.0 plus the first batch of refreshed technical content so we can gather feedback on flow, discoverability, and overall developer experience improvements.

what to review and how - we are trying a three-label system so each reviewer knows what kind of feedback is actually actionable right now:

Label	Description
S	structural / design review (layout, components, readability)
N	navigation / IA / flow review (top-nav, sidebar, breadcrumbs, cross-links)
T	technical-content review (accuracy, completeness, examples)

Section	Ready	Notes	Done
Homepage	S, N, T	mostly unchanged, ready for any kind of review	✅
Clarinet	S, N	~95% technical content complete
Chainhook	S	~70% technical content complete
Contract Monitoring		~80% technical content complete
Bitcoin Indexer		~50% technical content complete
API references	S, N, T	reference pages overhauled and playground refreshed.
API page content		old guide pages untouched. not ready for full review
ai/llms.txt	S, N, T	additional eval testing also welcome
Stacks.js	S	needs updated content
Clarinet JS SDK / Browser	S, N, T	ready across the board
Stacks Blockchain Client		not ready

what is excluded in phase I - these areas and sections stay frozen; no feedback needed until phase II or later:

1. guides
2. snippets
3. clarity
4. hiro archive