feat(git): /git overview page and diff viewer

Add git module with repo status overview (/git) and per-repo detail page
(/git/[repo]) featuring a color-coded diff viewer (+ green, - red).
Reads repo paths from REPO_PATHS env var, calls ops-agent git_status and
git_diff commands. Status badges: clean (green), dirty (orange),
behind-origin (blue).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/parse-git.ts

@@ -0,0 +1,46 @@
+export interface RepoStatus {
+  branch: string
+  /** Number of commits ahead of upstream (undefined if no upstream) */
+  ahead?: number
+  /** Number of commits behind upstream (undefined if no upstream) */
+  behind?: number
+  /** True when there are uncommitted changes */
+  dirty: boolean
+}
+
+/**
+ * Parses `git status --short --branch` output into a RepoStatus.
+ *
+ * First line format:  ## main...origin/main [ahead N, behind M]
+ * Remaining lines:    XY path  (presence means dirty)
+ */
+export function parseGitStatus(output: string): RepoStatus {
+  const lines = output.trim().split('\n').filter(Boolean)
+
+  let branch = 'unknown'
+  let ahead: number | undefined
+  let behind: number | undefined
+  let dirty = false
+
+  for (const line of lines) {
+    if (line.startsWith('## ')) {
+      const rest = line.slice(3)
+      // "No commits yet on main" or "HEAD (no branch)"
+      const trackMatch = rest.match(/^([^.]+)\.\.\.(\S+)/)
+      if (trackMatch) {
+        branch = trackMatch[1]
+      } else {
+        branch = rest.split(' ')[0]
+      }
+      const aheadMatch = rest.match(/ahead (\d+)/)
+      const behindMatch = rest.match(/behind (\d+)/)
+      if (aheadMatch) ahead = parseInt(aheadMatch[1], 10)
+      if (behindMatch) behind = parseInt(behindMatch[1], 10)
+    } else {
+      // Any non-header line means there are changes
+      dirty = true
+    }
+  }
+
+  return { branch, ahead, behind, dirty }
+}