feat: on-demand external script analysis + code viewer; refactor form analysis to rule engine

- API: add `POST /api/analyze_script` (app/blueprints/api.py)
  - Fetch one external script to artifacts, run rules, return findings + snippet
  - Uses new ExternalScriptFetcher (results_path aware) and job UUID
  - Returns: { ok, final_url, status_code, bytes, truncated, sha256, artifact_path, findings[], snippet, snippet_len }
  - TODO: document in openapi/openapi.yaml

- Fetcher: update `app/utils/external_fetch.py`
  - Constructed with `results_path` (UUID dir); writes to `<results_path>/scripts/fetched/<index>.js`
  - Loads settings via `get_settings()`, logs via std logging

- UI (results.html):
  - Move “Analyze external script” action into **Content Snippet** column for external rows
  - Clicking replaces button with `<details>` snippet, shows rule matches, and adds “open in viewer” link
  - Robust fetch handler (checks JSON, shows errors); builds viewer URL from absolute artifact path

- Viewer:
  - New route: `GET /view/artifact/<run_uuid>/<path:filename>` (app/blueprints/ui.py)
  - New template: Monaco-based read-only code viewer (viewer.html)
  - Removes SRI on loader to avoid integrity block; loads file via `raw_url` and detects language by extension

- Forms:
  - Refactor `analyze_forms` to mirror scripts analysis:
    - Uses rule engine (`category == "form"`) across regex/function rules
    - Emits rows only when matches exist
    - Includes `content_snippet`, `action`, `method`, `inputs`, `rules`
  - Replace legacy plumbing (`flagged`, `flag_reasons`, `status`) in output
  - Normalize form function rules to canonical returns `(bool, Optional[str])`:
    - `form_action_missing`
    - `form_http_on_https_page`
    - `form_submits_to_different_host`
    - Add minor hardening (lowercasing hosts, no-op actions, clearer reasons)

- CSS: add `.forms-table` to mirror `.scripts-table` (5 columns)
  - Fixed table layout, widths per column, chip/snippet styling, responsive tweaks

- Misc:
  - Fix “working outside app context” issue by avoiding `current_app` at import time (left storage logic inside routes)
  - Add “View Source” link to open page source in viewer

Refs:
- Roadmap: mark “Source code viewer” done; keep TODO to add `/api/analyze_script` to OpenAPI

app/utils/settings.py

@@ -39,6 +39,14 @@ BASE_DIR = Path(__file__).resolve().parent.parent
 DEFAULT_SETTINGS_FILE = BASE_DIR / "config" / "settings.yaml"
 
 # ---------- CONFIG DATA CLASSES ----------
+@dataclass
+class External_FetchConfig:
+    enabled: bool = True
+    max_total_mb: int = 5 
+    max_time_ms: int = 3000 
+    max_redirects: int = 3 
+    concurrency: int = 3 
+
 @dataclass
 class UIConfig:
     snippet_preview_len: int = 160
@@ -61,6 +69,7 @@ class AppConfig:
 class Settings:
     cache: Cache_Config = field(default_factory=Cache_Config)
     ui: UIConfig = field(default_factory=UIConfig)
+    external_fetch: External_FetchConfig = field(default_factory=External_FetchConfig)
     app: AppConfig = field(default_factory=AppConfig)
 
     @classmethod