docs: add validated architecture visuals

[kevinten10]

Summary

• replace the README ASCII overview with a validated AnyCap architecture diagram
• add AnyCap diagrams for capability preflight and Provider conformance
• add deterministic SVGs for the exact lifecycle state machine and Local Provider security boundary
• add text equivalents, visual provenance, SHA-256 integrity records, and consumer-width QA
• scan generated image metadata during pnpm sanitize

Visual validation

• generated two candidates for each AnyCap diagram and retained only topology-correct images
• direct inspection at 2048x1152 and approximately 900px consumer width
• independent AnyCap image-read: PASS for text, edges, boundaries, and peer relationships
• PNG metadata stripped; request IDs, account metadata, local paths, credentials, and internal identifiers absent

Repository verification

• pnpm check passed, including 83 tests and coverage thresholds
• documentation validation: 24 Markdown files and 17 managed IDs
• pnpm sanitize and production dependency audit passed

All visuals are derived only from the public repository contract. No private implementation or provider topology is represented.