docs: update for session kinds, Design Contracts, and Implementation Runs
Covers everything the plugin gained since the last wiki refresh:
- SERP AI Sessions rewritten around the current session-kind model —
multi-session lists per scope, live status icons, Claude Code/Codex
agent backends, session spawning, SERP AI Configuration editor, and
the new SERP AI Settings panel.
- New Design Contracts page: the durable approval/implementation
lifecycle above session summaries, plus Design Sync/Reconciliation
and the headless Design Draft session for existing projects.
- New Implementation Runs page: the SERP AI Runs panel that batch-plans
and spawns implementation sessions from design/state drift.
- Explorer rewritten for the current tree (Specs/Deployments/Services/
HMI, Tests and Sequences folders, inline deployment diagrams).
- Test Engine documents generated GTest component tests produced from
sequence diagrams.
- AI-Driven Development, Plugin Overview, Home, and the runtime/
generated-code pages updated to match; stale serp_* MCP tool names
fixed to the current serp.* dotted form throughout.
docs: add causal preambles to core concepts, move generator coverage section to top, reframe SerpIDL and plugin intros
docs: add logo and screenshots to plugin pages
docs: initial wiki — 36 pages covering framework, SerpIDL, generator, plugin, examples