feat: rewrite README to align with new website messaging

[BYK]

Summary

Rewrites the README to align with the new website messaging while preserving the project's technical depth and research roots.

Key changes

Messaging alignment:

• Opens with pain + solution ("Stop re-explaining your project to your AI") instead of architecture
• Adds the unified pipeline angle: context management and memory are the same problem, not two separate tools
• "Why" section now explains the gap between memory-only and context-only approaches

New sections:

• What to expect — rewritten with user-facing benefits: infinite sessions, cost savings, decisions that stick, conversation import, any-provider compatibility, team knowledge via Lore Cloud
• Quick Start — lore run as the primary entry point, with OpenCode/Pi plugin setup as alternatives
• Cost efficiency — batch APIs (50% off), cheaper worker models, predictive cache warming, 3-block system prompt caching, compaction elimination, content deduplication
• lore import — documents conversation import from 7 agents (Claude Code, Codex, Aider, Cline, Continue, OpenCode, Pi)

Fixes:

• All AGENTS.md references → .lore.md
• All DEVELOPMENT_CONTEXT.md references removed
• Configuration example updated (agentsFile path → .lore.md)
• License confirmed as FSL-1.1-Apache-2.0

Preserved:

• Full research credits in "Standing on the shoulders of"
• Complete benchmark tables and methodology
• "How we got here" project history (v1→v4)
• Technical depth: three-tier architecture, gradient context manager, recall tool, CLI reference, lat.md compatibility
• Configuration reference with all options