chore: bump version to 0.8.0-alpha + v0.8.0-alpha release notes

Version bumped in all five places (core/cli/tauri-app Cargo.toml,
tauri.conf.json, Android versionName + versionCode 8000).

download.html carries the v0.8.0-alpha release block: registry + greeting
comments as the headline, the manifest privacy fix and persona-split bug
family, comment ingest verification, and the protocol slimming. States
plainly that v0.8 cannot talk to v0.7.x and the anchor moves with it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LGiPD2cF75mnvneSCjdDC5

crates/cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "itsgoin-cli"
-version = "0.7.3"
+version = "0.8.0-alpha"
 edition = "2021"
 
 [[bin]]

crates/core/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "itsgoin-core"
-version = "0.7.3"
+version = "0.8.0-alpha"
 edition = "2021"
 
 [dependencies]

crates/tauri-app/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "itsgoin-desktop"
-version = "0.7.3"
+version = "0.8.0-alpha"
 edition = "2021"
 
 [lib]

crates/tauri-app/tauri.conf.json

@@ -1,6 +1,6 @@
 {
   "productName": "itsgoin",
-  "version": "0.7.3",
+  "version": "0.8.0-alpha",
   "identifier": "com.itsgoin.app",
   "build": {
     "frontendDist": "../../frontend",