feat: HTTP server for exporting Arborix bundles

Introduces a read-only HTTP server (WAI/Warp) backed by the content
store, exposing three bundle-export endpoints:

- GET /bundle/name/:name   — export by stored term name
- GET /bundle/hash/:hash   — export by full Merkle hash
- GET /terms               — plain-text listing (debug)

Also adds `tricu server` (aka `--serve`) CLI mode, move `resolveExportTarget` /
 `namesForHash` / `looksLikeHash` out of `Main.hs` into `ContentStore.hs`,
and cleans up unused exports and imports across `FileEval.hs` and `Wire.hs`.

tricu.cabal

@@ -51,15 +51,20 @@ executable tricu
     , filepath
     , fsnotify
     , haskeline
+    , http-types
     , megaparsec
     , memory
     , mtl
+    , servant
     , sqlite-simple
+    , stm
     , tasty
     , tasty-hunit
     , text
     , time
     , transformers
+    , wai
+    , warp
     , zlib
   other-modules:
     ContentStore
@@ -70,6 +75,7 @@ executable tricu
     Paths_tricu
     REPL
     Research
+    Server
     Wire
   default-language: Haskell2010
 
@@ -99,15 +105,20 @@ test-suite tricu-tests
     , filepath
     , fsnotify
     , haskeline
+    , http-types
     , megaparsec
     , memory
     , mtl
+    , servant
     , sqlite-simple
+    , stm
     , tasty
     , tasty-hunit
     , text
     , time
     , transformers
+    , warp
+    , wai
     , zlib
   default-language:    Haskell2010
   other-modules:
@@ -119,4 +130,5 @@ test-suite tricu-tests
     Paths_tricu
     REPL
     Research
+    Server
     Wire