feat: extract shared infrastructure from shared_lib

Phase 1-3 of decoupling plan:
- Shared DB, models, infrastructure, browser, config, utils
- Event infrastructure (domain_events outbox, bus, processor)
- Structured logging
- Generic container concept (container_type/container_id)
- Alembic migrations for all schema changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

utils.py

@@ -0,0 +1,96 @@
+import re
+from bs4 import BeautifulSoup
+import json
+import os
+from typing import Iterable, Union, List
+
+from quart import request
+
+def soup_of(html: str) -> BeautifulSoup:
+    return BeautifulSoup(html, "lxml")
+
+def normalize_text(s: str) -> str:
+    return re.sub(r"\s+", " ", (s or "").strip())
+
+def log(msg: str) -> None:
+    print(msg, flush=True)
+
+def ensure_dir(path: str) -> None:
+    os.makedirs(path, exist_ok=True)
+
+def dump_json(path: str, data) -> None:
+    ensure_dir(os.path.dirname(path))
+    with open(path, "w", encoding="utf-8") as f:
+        json.dump(data, f, ensure_ascii=False, indent=2)
+
+
+def _join_url_parts(parts: List[str]) -> str:
+    parts = [p for p in parts if p is not None and p != ""]
+    if not parts:
+        return ""
+
+    # Preserve scheme like "https://"
+    m = re.match(r"^([a-zA-Z][a-zA-Z0-9+.-]*://)(.*)$", parts[0])
+    if m:
+        scheme, first = m.group(1), m.group(2)
+    else:
+        scheme, first = "", parts[0]
+
+    cleaned = [first.strip("/")]
+    for seg in parts[1:]:
+        seg = str(seg)
+        if seg.startswith("?") or seg.startswith("#"):
+            cleaned[-1] = cleaned[-1] + seg  # attach query/fragment
+        else:
+            cleaned.append(seg.strip("/"))
+
+    url = scheme + "/".join(s for s in cleaned if s != "")
+
+    # Preserve trailing slash if caller's last segment had one (and isn't ? or #)
+    last = str(parts[-1])
+    if last.endswith("/") and not last.startswith(("?", "#")) and not url.endswith("/"):
+        url += "/"
+
+    return url
+
+def hx_fragment_request() -> bool:
+    return request.headers.get("HX-Request", "").lower() == "true"
+def route_prefix():
+    return f"{request.scheme}://{request.host}/{request.headers.get('x-forwarded-prefix', '/')}"
+
+def join_url(value: Union[str, Iterable[str]]):
+  if isinstance(value, str):
+      parts = [value]
+  else:
+      parts = list(value)
+  return _join_url_parts(parts)
+
+def host_url(value: str='', no_slash=False):
+    """
+    Join g.route with value and ensure the resulting URL has a trailing slash
+    on the path, but never after query/fragment.
+
+    Examples:
+      http://jjj          -> http://jjj/
+      http://jjj?hello    -> http://jjj/?hello
+      /foo                -> /foo/
+      /foo?x=1#frag       -> /foo/?x=1#frag
+    """
+    url = join_url([route_prefix(), value])
+
+    # Ensure trailing slash on the PATH (before ? or #)
+    # Split into: base (no ?/#), optional ?query, optional #fragment
+    if no_slash:
+        return url
+    m = re.match(r'^(?P<base>[^?#]*)(?P<qs>\?[^#]*)?(?P<frag>#.*)?$', url)
+    if not m:
+        return url  # fallback: return as-is
+
+    base = m.group('base') or ""
+    qs = m.group('qs') or ""
+    frag = m.group('frag') or ""
+
+    if base and not base.endswith('/'):
+        base += '/'
+
+    return f"{base}{qs}{frag}"