Add multi-route donor->recipient support, fix VK hashtag truncation

Posts can now be sourced from multiple VK groups, each routed to its own
Telegram/MAX destination(s) with independent on/off switches, configured
via data/routes.json (supports // line comments). Falls back to a single
route auto-generated from the legacy VK_SOURCE/TG_CHAT_ID/MAX_CHAT_ID env
vars if routes.json doesn't exist yet, so existing deployments keep working.

Routes are processed strictly sequentially within a cycle (no concurrency)
to keep flood control on VK/TG/MAX correct, since bot tokens are shared
across routes. DB schema gains route_id in the posts uniqueness key so the
same VK donor can safely feed multiple routes without status collisions.

Also removes the trailing-hashtag-stripping logic in text_formatter, which
was silently deleting VK posts' own hashtags whenever COMMON_TAGS wasn't
configured (it always wasn't) - posts are now forwarded unchanged.

src/text_formatter.py

@@ -34,18 +34,6 @@ def clean_dividers(lines: list[str]) -> list[str]:
     return ["" if sep_pattern.match(line) else line for line in lines]
 
 
-def strip_trailing_hashtags(text: str) -> str:
-    lines = text.rstrip().splitlines()
-    while lines and not lines[-1].strip():
-        lines.pop()
-    if not lines:
-        return ""
-    parts = lines[-1].split()
-    if parts and all(part.startswith("#") for part in parts):
-        lines.pop()
-    return "\n".join(lines).rstrip()
-
-
 # Matches VK bracket markup: [club123|Name], [id123|Name], [public123|Name],
 # [event123|Name] or a raw-URL bracket link [https://example.com|Title]
 _VK_LINK_RE = re.compile(
@@ -213,8 +201,7 @@ def format_post_text(
     footer = normalize_wrapper_text(settings.footer_text if footer is None else footer, parse_mode)
     tags = normalize_wrapper_text(settings.common_tags if tags is None else tags, parse_mode)
 
-    body = strip_trailing_hashtags(raw_text)
-    lines = clean_dividers(body.splitlines())
+    lines = clean_dividers(raw_text.splitlines())
 
     title_idx: Optional[int] = None
     for idx, line in enumerate(lines):