docs: reposition PaperCache as 'knowledge manager' instead of 'scratchpad' across README, llms.txt, and PHILOSOPHY.md

Author: VariableThe

PHILOSOPHY.md

@@ -1,7 +1,7 @@
 # Our Philosophy
 
 ### 1. **Your Thoughts Are Ephemeral**
-A scratchpad shouldn't feel like a database. PaperCache is designed for the temporary, the messy, and the in-between. It spawns when you need it, vanishes when you're done, and gets out of your way.
+A knowledge tool shouldn't feel like a database. PaperCache is designed for the temporary, the messy, and the in-between. It spawns when you need it, vanishes when you're done, and gets out of your way.
 
 ### 2. **Active > Passive**
 PaperCache is active. It evaluates your math in real-time, queries AI inline, links your notes automatically, and visualizes your knowledge graph. Your notes should work for you, not just store your words.
@@ -41,4 +41,4 @@ PaperCache makes specific, intentional choices:
 ---
 
 ### The Bottom Line
-PaperCache is a simple, polished tool built by a developer to solve a personal need. It's the floating scratchpad I always wanted but didn't want to pay a subscription for—so I built it myself, and now it's yours too.
+PaperCache is a simple, polished tool built by a developer to solve a personal need. It's the floating knowledge manager I always wanted but didn't want to pay a subscription for—so I built it myself, and now it's yours too.

README.md

@@ -2,7 +2,7 @@
   <img src="public/icon.png" width="128" height="128" alt="PaperCache Logo">
 
   # PaperCache
-  **A floating markdown scratchpad for developers and power users.**
+  **A floating knowledge manager for developers and power users.**
 </div>
 
 > **Why PaperCache?** I saw a cool tool called Antinote, but it was locked behind a paywall. I wanted something similar that was open source and fit my own workflow perfectly, so I built PaperCache to match it. It solved my problem, and I figured other people might have the exact same needs, so I made it completely free and open for everyone. Read the full story in our [Core Philosophy](PHILOSOPHY.md).

llms.txt

@@ -1,6 +1,6 @@
 # PaperCache
 
-> A floating markdown scratchpad for developers and power users.
+> A floating knowledge manager for developers and power users.
 
 PaperCache is a Tauri-based application built with an obsession for performance, privacy, and polish. It is designed to be a frictionless note-taking tool that lives in the background and is summoned via a global hotkey.