refactor!: rebrand bterminal to agor (agents-orchestrator)

Rename Cargo crates (bterminal-core→agor-core, bterminal-relay→agor-relay),
env vars (BTERMINAL_*→AGOR_*), config paths (~/.config/agor), CSS custom
properties, plugin API object, package names, and all documentation.

BREAKING CHANGE: config/data paths changed from bterminal to agor.

.github/workflows/e2e.yml

@@ -6,7 +6,7 @@ on:
     paths:
       - 'v2/src/**'
       - 'v2/src-tauri/**'
-      - 'v2/bterminal-core/**'
+      - 'v2/agor-core/**'
       - 'v2/tests/e2e/**'
       - '.github/workflows/e2e.yml'
   pull_request:
@@ -14,7 +14,7 @@ on:
     paths:
       - 'v2/src/**'
       - 'v2/src-tauri/**'
-      - 'v2/bterminal-core/**'
+      - 'v2/agor-core/**'
       - 'v2/tests/e2e/**'
   workflow_dispatch:
 
@@ -134,19 +134,19 @@ jobs:
       - name: Run E2E tests (Phase A — deterministic)
         working-directory: v2
         env:
-          BTERMINAL_TEST: '1'
+          AGOR_TEST: '1'
           SKIP_BUILD: '1'
         run: |
           xvfb-run --auto-servernum --server-args="-screen 0 1920x1080x24" \
             npx wdio tests/e2e/wdio.conf.js \
-            --spec tests/e2e/specs/bterminal.test.ts \
+            --spec tests/e2e/specs/agor.test.ts \
             --spec tests/e2e/specs/agent-scenarios.test.ts
 
       - name: Run E2E tests (Phase B — multi-project)
         if: success()
         working-directory: v2
         env:
-          BTERMINAL_TEST: '1'
+          AGOR_TEST: '1'
           SKIP_BUILD: '1'
         run: |
           xvfb-run --auto-servernum --server-args="-screen 0 1920x1080x24" \
@@ -158,7 +158,7 @@ jobs:
         if: success() && env.ANTHROPIC_API_KEY != ''
         working-directory: v2
         env:
-          BTERMINAL_TEST: '1'
+          AGOR_TEST: '1'
           SKIP_BUILD: '1'
           ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
         run: |