feat: convert mdbook to Grav format (199 pages)

Converted from mdbook src/ in input/ to Grav pages/ format:
- Added YAML frontmatter to all pages
- Created numbered folder structure (01.home, 02.Bylaws.*, etc.)
- Preserved all content from Bylaws, Handbook, OperatingAgreements,
  Policies, and JointVenture sections

super ultra big merge completed. scope of work clearly defined. let's go build!

Assisted-by: GLM-5 via Crush <crush@charm.land>

pages/131.Handbook.SourceMaterial.strategy.investors/default.md

@@ -0,0 +1,51 @@
+---
+title: 'Series A'
+menu: 'Series A'
+---
+
+---
+title: Investors
+sidebar: Handbook
+showTitle: true
+---
+PostHog are proud to have many world-class investors.
+
+## Series A
+
+We raised a \$9M Series A round, led by Alphabet’s VC firm GV, with participation from YCombinator's Continuity Fund and Tapas Capital.
+
+We brought on board Jason Warner (CTO GitHub) as an investor.
+
+## Seed
+
+We raised a \$3M seed round, led by YCombinator and 1984 VC.
+
+We are also grateful to work with the support of the following:
+
+* Unusual Ventures
+* Liquid2 Ventures
+* Kima Ventures
+* Sunflower Ventures
+* Uncorrelated
+* Tapas Capital
+* SV Angel
+* Twenty Two Ventures
+
+## Angels
+
+We have brought on a brilliant group of angel investors throughout PostHog's life:
+
+* David Buxton (founder of Arachnys)
+* Dalton Caldwell (founder of imeem / YC Head of Admissions)
+* David Cramer (founder of Sentry)
+* Brad Flora (founder of PerfectAudience)
+* Adam Goldstein (founder of Hipmunk)
+* Solomon Hykes (founder of Docker)
+* Rujul Zaparde (founder of FlightCar)
+* Many more (add yourself via a pull request!)
+
+## Interested?
+
+If you'd like to talk to us about an investment in PostHog, please drop us a line at [investors@posthog.com](mailto:investors@posthog.com).
+
+If you are a startup and want an introduction or advice, please email us at [hey@posthog.com](mailto:hey@posthog.com). We can get very busy but we'll do our best to at least respond in all cases.