refactor(renderer): move diff rendering into its own module

views.js sat at the project's 750-line limit, so the diff cap in the previous
commit pushed it over and every further change would have meant shaving
comments elsewhere. That is the file asking for decomposition, which is what the
architecture audit says to do.

Diff rendering is self-contained: the line cap, the line classifier and the
change-map illustration depend on nothing in views.js beyond ui and escapeHtml.
They now live in src/renderer/diff-view.js and are registered in index.html and
in the three renderer file lists that scan the bridge surface, so anything added
there is covered by the existing contract tests.

views.js drops from 755 to 714 lines and no source file exceeds 750 again. The
nested ternary that classified a diff line became a named function with guard
clauses on the way.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

reports/architecture-audit.json

@@ -1,27 +1,10 @@
 {
-  "generatedAt": "2026-08-23T12:44:33.101Z",
+  "generatedAt": "2026-08-23T12:51:31.496Z",
   "thresholds": {
     "preferredMaximumLines": 750,
     "justificationRequiredLines": 1000
   },
-  "over750": [
-    {
-      "file": "src/renderer/views.js",
-      "lines": 759,
-      "branches": 57,
-      "functions": 159,
-      "ipcHandlers": 0,
-      "responsibilities": [
-        "inventory",
-        "deployment",
-        "git",
-        "renderer",
-        "security",
-        "updates"
-      ],
-      "hotspotScore": 97
-    }
-  ],
+  "over750": [],
   "over1000": [],
   "cyclomaticHotspots": [
     {
@@ -193,9 +176,9 @@
     },
     {
       "file": "src/renderer/views.js",
-      "lines": 759,
-      "branches": 57,
-      "functions": 159,
+      "lines": 715,
+      "branches": 53,
+      "functions": 152,
       "ipcHandlers": 0,
       "responsibilities": [
         "inventory",
@@ -205,7 +188,7 @@
         "security",
         "updates"
       ],
-      "hotspotScore": 97
+      "hotspotScore": 93
     },
     {
       "file": "src/main/ipc.cjs",

reports/architecture-audit.md

@@ -1,12 +1,12 @@
 # ForgeFlow architecture audit
 
-Generated 2026-08-23T12:44:33.101Z. Complexity is a deterministic decision-point count used for hotspot ranking, not a claim of exact McCabe complexity.
+Generated 2026-08-23T12:51:31.496Z. Complexity is a deterministic decision-point count used for hotspot ranking, not a claim of exact McCabe complexity.
 
 ## Files above 750 lines
 
 | File | Lines | Decisions | Functions | IPC handlers | Responsibilities |
 |---|---:|---:|---:|---:|---|
-| `src/renderer/views.js` | 759 | 57 | 159 | 0 | inventory, deployment, git, renderer, security, updates |
+No findings.
 
 ## Files above 1,000 lines