feat: add merge_all_wren utility, strutil demo, and 7 new API manual pages

Add WrenFileReader class in apps/merge_all_wren.wren for recursive .wren file discovery and content printing. Introduce example/strutil_demo.wren demonstrating case conversion, hex encoding, SHA256 hashing, string repetition, padding, HTML/JSON escaping, and URL encoding/decoding. Create manual/api pages for argparse, dataset, html, markdown, uuid, wdantic, and web modules. Update manual/api/index.html sidebar and module count from 21 to 28, adding links and cards for the new modules.

test/web/router_advanced.wren

@@ -0,0 +1,42 @@
+// retoor <retoor@molodetz.nl>
+
+import "web" for Router
+
+var router = Router.new()
+
+router.get("/api/v1/*", Fn.new { |r| "wildcard" })
+router.put("/users/:id", Fn.new { |r| "put user" })
+router.delete("/users/:id", Fn.new { |r| "delete user" })
+router.patch("/users/:id", Fn.new { |r| "patch user" })
+router.post("/users", Fn.new { |r| "create user" })
+
+var m1 = router.match("GET", "/api/v1/anything")
+System.print(m1 != null) // expect: true
+
+var m2 = router.match("GET", "/api/v1/nested/path")
+System.print(m2 != null) // expect: true
+
+var m3 = router.match("PUT", "/users/456")
+System.print(m3 != null) // expect: true
+System.print(m3["params"]["id"]) // expect: 456
+
+var m4 = router.match("DELETE", "/users/789")
+System.print(m4 != null) // expect: true
+System.print(m4["params"]["id"]) // expect: 789
+
+var m5 = router.match("PATCH", "/users/101")
+System.print(m5 != null) // expect: true
+
+var m6 = router.match("POST", "/users")
+System.print(m6 != null) // expect: true
+
+var m7 = router.match("OPTIONS", "/users")
+System.print(m7 == null) // expect: true
+
+var router2 = Router.new()
+router2.get("/posts/:postId/comments/:commentId", Fn.new { |r| "comment" })
+
+var m8 = router2.match("GET", "/posts/10/comments/20")
+System.print(m8 != null) // expect: true
+System.print(m8["params"]["postId"]) // expect: 10
+System.print(m8["params"]["commentId"]) // expect: 20