Replace non-free direct-img images with free (PD/CC0) ones

Swap every direct-img.link image across 7 articles and the site OG/author
images for hand-picked free.direct-img.link equivalents, update alt text to
match, and point the writer template at the free host.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

articles/the-dpi-sweet-spot/index.md

@@ -4,7 +4,7 @@ slug: the-dpi-sweet-spot
 date: 2026-08-31
 author: "[Renox](/author/renox/) and Kimi K3"
 description: "A theory of DPI as a tremor filter: why 400 feels stable, why 800 exposes shaky hands, why latency still matters, and why 450–550 is the suspiciously precise sweet range."
-header_image: https://direct-img.link/aim+crosshair+mouse+sensor+cyber+minimal
+header_image: https://free.direct-img.link/esports?i=8
 tags:
   - DPI
   - aim
@@ -18,7 +18,7 @@ tags:
 
 # The Mouse DPI Sweet Spot Is 500
 
-![Crosshair over glowing mouse sensor](https://direct-img.link/aim+crosshair+mouse+sensor+cyber+minimal)
+![Gamer at a glowing keyboard, hand on the mouse](https://free.direct-img.link/esports?i=8)
 
 The theory started simply: DPI is not just “sensitivity.” DPI is a sampling grid. It decides how much physical hand motion is required before the mouse reports anything at all.
 
@@ -28,7 +28,7 @@ Most people ask: “What DPI is fastest?”
 
 The better question is: **what DPI is high enough to preserve fine control, but low enough to stop your nervous system from leaking into your aim?**
 
-![Nervous aim meme](https://direct-img.link/nervous+sweating+meme)
+![Edvard Munch's The Scream](https://free.direct-img.link/the+scream+munch?i=1)
 
 ## Step 1: DPI is a distance threshold
 
@@ -109,7 +109,7 @@ That bracket — **~423 to ~508 DPI** — is uncomfortably close to the proposed
 
 That was the moment the theory stopped sounding like numerology. We did not pick 450–550 first and reverse-engineer a justification. The tremor math independently landed on almost the same neighborhood. **Suspiciously close.** Close enough that the sweet spot hypothesis deserved to be treated as a real model, not preference folklore.
 
-![Galaxy brain realization](https://direct-img.link/galaxy+brain+realization+meme)
+![The Flammarion engraving: a traveler pokes his head through the sky](https://free.direct-img.link/flammarion+engraving?i=2)
 
 ## Step 4: latency pulls the other way