feat: add ticket context prompt formatter (Task 7)

format_ticket_context_for_prompt() in services/psa/ticket_context.py
serializes TicketContext into structured text for AI system prompts,
with 10-note limit, 200-char text previews, and human-readable timestamps.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/psa/ticket_context.py

@@ -0,0 +1,84 @@
+"""Format PSA ticket context as structured text for AI system prompts."""
+from __future__ import annotations
+
+from app.schemas.psa_context import TicketContext
+
+
+def format_ticket_context_for_prompt(ctx: TicketContext) -> str:
+    """Serialize a TicketContext into a structured text block for AI prompts."""
+    lines: list[str] = ["=== TICKET CONTEXT ==="]
+
+    # Ticket summary line
+    t = ctx.ticket
+    lines.append(f'Ticket: #{t.id} — "{t.summary}"')
+    lines.append(f"Status: {t.status} | Priority: {t.priority}")
+    lines.append(f"Board: {t.board}")
+    if t.sla:
+        lines.append(f"SLA Deadline: {t.sla}")
+    if t.resources:
+        lines.append(f"Assigned To: {t.resources}")
+
+    # Company block
+    lines.append("")
+    c = ctx.company
+    lines.append(f"Client: {c.name}")
+    if c.site:
+        lines.append(f"Site: {c.site}")
+    if c.address:
+        lines.append(f"Address: {c.address}")
+    if c.phone:
+        lines.append(f"Phone: {c.phone}")
+    if c.type:
+        lines.append(f"Type: {c.type}")
+    if c.territory:
+        lines.append(f"Territory: {c.territory}")
+
+    # Contact block
+    if ctx.contact:
+        contact = ctx.contact
+        contact_parts = [contact.name]
+        if contact.email:
+            contact_parts.append(f"({contact.email})")
+        if contact.title:
+            contact_parts.append(f"— {contact.title}")
+        contact_line = " ".join(contact_parts)
+        if contact.phone:
+            contact_line += f" — {contact.phone}"
+        lines.append("")
+        lines.append(f"Contact: {contact_line}")
+
+    # Devices
+    if ctx.configurations:
+        lines.append("")
+        lines.append("Devices:")
+        for cfg in ctx.configurations:
+            parts = [cfg.device_identifier]
+            if cfg.type:
+                parts.append(cfg.type)
+            if cfg.os_type:
+                parts.append(cfg.os_type)
+            if cfg.ip_address:
+                parts.append(cfg.ip_address)
+            lines.append("- " + " | ".join(parts))
+
+    # Recent Notes (limit 10, text preview 200 chars)
+    if ctx.notes:
+        lines.append("")
+        lines.append("Recent Notes:")
+        for note in ctx.notes[:10]:
+            date_str = note.date_created.strftime("%b %d, %I:%M %p")
+            member_str = f"{note.member}: " if note.member else ""
+            text_preview = note.text[:200]
+            if len(note.text) > 200:
+                text_preview += "..."
+            lines.append(f"- [{date_str}] {member_str}{text_preview}")
+
+    # Related open tickets
+    if ctx.related_tickets:
+        lines.append("")
+        lines.append("Related Open Tickets:")
+        for rt in ctx.related_tickets:
+            lines.append(f'- #{rt.id}: "{rt.summary}" ({rt.status}, {rt.priority})')
+
+    lines.append("=== END CONTEXT ===")
+    return "\n".join(lines)