docs: Remove legacy Classic and Universal Input docs (#823)

* docs: remove unsupported Classic Input documentation

Co-Authored-By: Oz <oz-agent@warp.dev>

* docs: address Classic Input cleanup review

Co-Authored-By: Oz <oz-agent@warp.dev>

* docs: remove legacy Universal Input references

Co-Authored-By: Oz <oz-agent@warp.dev>

* docs: align remaining input terminology

Co-Authored-By: Oz <oz-agent@warp.dev>

* docs: handle trailing slash terminal redirect

---------

Co-authored-by: warp-agent-staging[bot] <240773466+warp-agent-staging[bot]@users.noreply.github.com>
Co-authored-by: Oz <oz-agent@warp.dev>
Co-authored-by: Hong Yi Chen <hongyi@warp.dev>

Author: 3 people

.agents/references/terminology.md

@@ -35,10 +35,10 @@
 # Feature names that are correctly Title Case (exceptions to sentence-case rule)
 PROPER_FEATURE_NAMES = {
     "Admin Panel", "Agent Management Panel", "Agent Mode", "Agent Profiles",
-    "Auto-detection Mode", "Cloud Agents",
+    "Cloud Agents",
     "Codebase Context", "Code Review", "Command Palette", "Global Rules",
     "Oz CLI", "Oz Platform", "Project Rules",
-    "Slash Commands", "Terminal Mode", "Universal Input", "Warp Drive",
+    "Slash Commands", "Warp Drive",
     "Warp Platform", "Automation Platform", "Warp Factories", "Factory MCP",
     "Computer Use", "Full Terminal Use", "Zero Data Retention", "Single Sign-On",
     "Blocks", "Block", "Tab Configs", "Tab Config",