refactor: consolidate bulk actions, URL assembly, and case-artefact filenames

Pulls three pattern groups into shared helpers so a rename or wire-format
tweak edits one file instead of 10+:

- BulkAction enum in doctate-common replaces the "close"/"analyze"/"reset"
  string literals that were duplicated between the bulk handler and 3
  attack/CSRF test files. FromStr preserves the exact "Unbekannte Aktion"
  error shape; the handler match is now exhaustive over the enum.
- join_url helper in doctate-common absorbs 7 identical
  trim_end_matches+format! call sites across client-core, client-desktop,
  server/transcribe (ollama, whisper), and server/analyze (llm).
- server/tests/common/artefacts.rs re-exports ONELINER_FILENAME
  (doctate-common), DOCUMENT_FILE + ANALYSIS_INPUT_FILE
  (doctate-server::analyze), and CLOSE_MARKER (doctate-server::paths) so
  test files reference the canonical name instead of inlining literals.

Also lifts client-desktop local duplication:
- paths.rs: project_path helper collapses 4 identical ProjectDirs chains
- main.rs: or_die helper replaces 4 eprintln!+exit(1) blocks
- app.rs: named RecordingContext struct replaces (Uuid, String) tuple
  at 3 sites around the ffmpeg-flush finalization path

Verification: 397 tests pass (baseline was 389; +8 for new unit tests on
BulkAction and join_url), 0 failed, 4 ignored (unchanged). clippy clean.

server/src/analyze/llm.rs

@@ -1,5 +1,6 @@
 use std::time::Duration;
 
+use doctate_common::join_url;
 use serde::{Deserialize, Serialize};
 use tracing::debug;
 
@@ -84,10 +85,7 @@ pub async fn chat_once(
     user_content: &str,
     timeout: Duration,
 ) -> Result<String, LlmError> {
-    let url = format!(
-        "{}/v1/chat/completions",
-        settings.base_url.trim_end_matches('/')
-    );
+    let url = join_url(settings.base_url, "/v1/chat/completions");
     debug!(%url, model = settings.model, "calling llm chat completions");
 
     let body = ChatRequest {

server/src/routes/bulk.rs

@@ -1,7 +1,9 @@
+use std::str::FromStr;
 use std::sync::Arc;
 
 use axum::extract::State;
 use axum::response::Redirect;
+use doctate_common::BulkAction;
 use doctate_common::timestamp::now_rfc3339;
 use serde::Deserialize;
 use tracing::{info, warn};
@@ -55,8 +57,16 @@ pub async fn handle_bulk_action(
 
     let user_root = config.data_path.join(&user.slug);
 
-    match form.action.as_str() {
-        "analyze" => {
+    // Parse the wire token into the shared enum so the match below is
+    // exhaustive at compile time. Keep the exact "Unbekannte Aktion"
+    // error shape the handler returned before the enum existed.
+    let action = BulkAction::from_str(&form.action).map_err(|err| {
+        warn!(slug = %user.slug, action = %err.0, "bulk: unknown action");
+        AppError::BadRequest("Unbekannte Aktion".into())
+    })?;
+
+    match action {
+        BulkAction::Analyze => {
             bulk_analyze(
                 &config,
                 &analyze_tx,
@@ -67,12 +77,8 @@ pub async fn handle_bulk_action(
             )
             .await
         }
-        "close" => bulk_close(&events_tx, &user.slug, &user_root, &form.case_ids).await,
-        "reset" => bulk_reset(&events_tx, &user.slug, &user_root, &form.case_ids).await,
-        other => {
-            warn!(slug = %user.slug, action = %other, "bulk: unknown action");
-            return Err(AppError::BadRequest("Unbekannte Aktion".into()));
-        }
+        BulkAction::Close => bulk_close(&events_tx, &user.slug, &user_root, &form.case_ids).await,
+        BulkAction::Reset => bulk_reset(&events_tx, &user.slug, &user_root, &form.case_ids).await,
     }
 
     Ok(Redirect::to("/web/cases"))

server/src/transcribe/ollama.rs

@@ -1,5 +1,6 @@
 use std::time::Duration;
 
+use doctate_common::join_url;
 use serde::{Deserialize, Serialize};
 use tracing::debug;
 
@@ -100,7 +101,7 @@ pub async fn generate_oneliner(
     transcript: &str,
     timeout: Duration,
 ) -> Result<String, OllamaError> {
-    let url = format!("{}/api/chat", ollama_url.trim_end_matches('/'));
+    let url = join_url(ollama_url, "/api/chat");
     debug!(%url, model, "generating oneliner");
 
     let body = ChatRequest {

server/src/transcribe/whisper.rs

@@ -1,6 +1,7 @@
 use std::path::Path;
 use std::time::Duration;
 
+use doctate_common::join_url;
 use reqwest::multipart::{Form, Part};
 use tracing::debug;
 
@@ -100,9 +101,8 @@ pub async fn transcribe(
         .filter(|s| !s.is_empty())
         .unwrap_or("de");
     let url = format!(
-        "{}/asr?output=txt&language={}",
-        whisper_url.trim_end_matches('/'),
-        language
+        "{}?output=txt&language={language}",
+        join_url(whisper_url, "/asr")
     );
     debug!(%url, "posting to whisper");