docs: update README with V3 Actions progress and nested search support

README.md

@@ -13,13 +13,18 @@ The API is currently in a transitional state between legacy (V1/V2) patterns and
 - **Core Principles:**
     - **`id_random` Primary:** All public communication uses URL-safe string IDs. Internal integer IDs are hidden.
     - **Nested URL Structure:** Enforces parent-child relationships (e.g., `/v3/crud/journal/{id}/entry/`).
+    - **Nested Advanced Search:** Full support for POST-based search on nested objects.
     - **Granular Dependencies:** Uses specialized FastAPI dependencies for Account Context, Pagination, Filtering, and Serialization.
     - **Advanced Search:** POST-based search with recursive logic and standardized operators.
     - **Schema Discovery:** Dynamic introspection of database and Pydantic models via `/v3/crud/{obj_type}/schema`.
 
 ### **V3 Actions**
 - **Path:** `/v3/action/`
-- Handles complex binary operations (uploads, streaming downloads) separately from standard metadata CRUD.
+- Handles complex binary operations and atomic business logic separately from standard metadata CRUD.
+- **Key Features:**
+    - **Atomic Event Uploads:** Marriage of physical storage and complex event relations in one request.
+    - **Content-Addressable Downloads:** Direct file retrieval by SHA256 hash for high-performance local caching.
+    - **Intelligent ID Resolution:** Standard download endpoints now automatically resolve container IDs (e.g., event_file) to underlying binaries.
 
 ### **Legacy API (V1/V2)**
 - **Path:** `/`, `/api/`, `/crud/`, `/v2/crud/`
@@ -89,7 +94,7 @@ The project maintains an exhaustive test suite under the `tests/` directory.
 ### **Active Workstreams**
 - **[Backend] API Deprecation:** Systematic pruning of orphaned routers and methods (ID: 111523094).
 - **[ID Vision]:** Phase 2 complete. String-ID standardization extended to Page, Post, Person, Journal, Contact, and User models.
-- **[V3 Migration]:** Transitioning Launcher file caching to V3 CRUD (ID: 173518010).
+- **[V3 Migration]:** Implementation of atomic event actions and hash-based retrieval for high-performance Launcher caching complete.
 
 ### **Known Bugs / Issues**
 - **Badge Rendering:**Corrupted numeric `id` fields in `event_badge_template` table causing template load failures in Svelte 5 views.