feat: add per-repository issue tracker config with Gitea support

Add ability to configure issue tracker (GitHub, GitLab, Gitea, Jira) per
repository at creation time and edit later via PATCH endpoint. Includes
new Gitea tracker implementation, edit modal in dashboard, and
tracker_token field on the repository model.

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

compliance-core/src/models/issue.rs

@@ -6,6 +6,7 @@ use serde::{Deserialize, Serialize};
 pub enum TrackerType {
     GitHub,
     GitLab,
+    Gitea,
     Jira,
 }
 
@@ -14,6 +15,7 @@ impl std::fmt::Display for TrackerType {
         match self {
             Self::GitHub => write!(f, "github"),
             Self::GitLab => write!(f, "gitlab"),
+            Self::Gitea => write!(f, "gitea"),
             Self::Jira => write!(f, "jira"),
         }
     }

compliance-core/src/models/repository.rs

@@ -28,6 +28,9 @@ pub struct TrackedRepository {
     pub tracker_type: Option<TrackerType>,
     pub tracker_owner: Option<String>,
     pub tracker_repo: Option<String>,
+    /// Optional per-repo PAT for the issue tracker (GitHub/GitLab/Jira)
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub tracker_token: Option<String>,
     /// Optional auth token for HTTPS private repos (PAT or password)
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub auth_token: Option<String>,
@@ -82,6 +85,7 @@ impl TrackedRepository {
             tracker_type: None,
             tracker_owner: None,
             tracker_repo: None,
+            tracker_token: None,
             last_scanned_commit: None,
             findings_count: 0,
             created_at: now,