feat: LinkedIn profile search engine (Django + React + Elasticsearch + ELK)

Full-stack implementation of the Cyberyan full-stack trial task.

Backend (Django 5 / DRF)
- Normalised PostgreSQL model (Profile, Company, School, Skill, Experience,
  Education) as the source of truth, with GIN + trigram indexes.
- Self-healing CSV reader: the supplied export carries an injected watermark
  column, missing columns, rows split by broken quoting and a duplicated
  header. A signature-scored Needleman-Wunsch alignment reconstructs 284 clean
  records out of 336 physical rows; only 10 rows parse correctly without it.
- Pluggable search layer (Strategy): Elasticsearch by default, PostgreSQL
  full-text search as a fallback selected by a single environment variable.
- Keyword search with per-field boosts, fuzziness and phrase boosting, six
  faceted filters (OR within a filter, AND across filters), an experience
  range, four sort orders, highlighting and facet aggregations.
- JWT auth with rotation + blacklist, three roles, PII masking, scoped rate
  limits, a single error envelope, OpenAPI schema and health probes.

Frontend (React 18 / TypeScript / Vite)
- Debounced search with type-ahead, faceted filter panel, result cards,
  profile drawer, URL-synced search state, automatic token refresh.
- Highlight snippets rendered without dangerouslySetInnerHTML.

Infrastructure
- Hardened multi-stage images (non-root, read-only rootfs, healthchecks).
- docker-compose for the full stack plus dev and production overlays.
- ELK: structured JSON logs shipped asynchronously to Logstash, routed per
  event type, with a composable index template and a Kibana setup script.

Quality
- 61 backend tests (85% coverage), ruff/black/bandit/mypy, ESLint + tsc,
  GitHub Actions running lint, tests and both image builds.
- Persian documentation: README plus architecture, search, API, data,
  security and operations guides.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GnFo6fNaHCTAkJbfcdkqtG

backend/apps/profiles/serializers.py

@@ -0,0 +1,119 @@
+"""Read-only serializers for profile payloads."""
+
+from __future__ import annotations
+
+from typing import Any
+
+from rest_framework import serializers
+
+from apps.profiles.models import Company, Education, Experience, Profile, School, Skill
+from apps.profiles.privacy import mask_emails, mask_phones
+
+
+class SkillSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Skill
+        fields = ("id", "name", "slug", "profile_count")
+
+
+class CompanySerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Company
+        fields = ("id", "name", "industry", "size", "founded", "website", "location_name")
+
+
+class SchoolSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = School
+        fields = ("id", "name", "type", "location_name")
+
+
+class ExperienceSerializer(serializers.ModelSerializer):
+    company = CompanySerializer(read_only=True)
+
+    class Meta:
+        model = Experience
+        fields = (
+            "id", "title", "title_role", "title_sub_role", "levels", "company", "company_name",
+            "start_date", "end_date", "start_year", "end_year", "is_primary", "location_name",
+            "summary",
+        )  # fmt: skip
+
+
+class EducationSerializer(serializers.ModelSerializer):
+    school = SchoolSerializer(read_only=True)
+
+    class Meta:
+        model = Education
+        fields = (
+            "id", "school", "school_name", "degrees", "majors", "minors", "gpa",
+            "start_date", "end_date", "end_year",
+        )  # fmt: skip
+
+
+class PIIMixin:
+    """Masks contact details unless the caller is allowed to see them."""
+
+    def _can_view_pii(self) -> bool:
+        request = self.context.get("request")  # type: ignore[attr-defined]
+        user = getattr(request, "user", None)
+        return bool(user and user.is_authenticated and user.can_view_pii)
+
+    def get_emails(self, obj: Profile) -> list[dict[str, str]]:
+        return obj.emails if self._can_view_pii() else mask_emails(obj.emails)
+
+    def get_phone_numbers(self, obj: Profile) -> list[str]:
+        return obj.phone_numbers if self._can_view_pii() else mask_phones(obj.phone_numbers)
+
+
+class ProfileListSerializer(PIIMixin, serializers.ModelSerializer):
+    """Compact representation used for result cards."""
+
+    headline = serializers.CharField(read_only=True)
+    company = serializers.CharField(source="current_company.name", default="", read_only=True)
+    skills = serializers.SerializerMethodField()
+    emails = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Profile
+        fields = (
+            "id", "full_name", "headline", "job_title", "job_title_role", "seniority_levels",
+            "company", "industry", "location_name", "location_country", "years_experience",
+            "linkedin_url", "skills", "emails",
+        )  # fmt: skip
+
+    def get_skills(self, obj: Profile) -> list[str]:
+        # ``prefetch_related`` in the view keeps this at one extra query total.
+        return [link.skill.name for link in obj.profile_skills.all()[:10]]
+
+
+class ProfileDetailSerializer(PIIMixin, serializers.ModelSerializer):
+    headline = serializers.CharField(read_only=True)
+    current_company = CompanySerializer(read_only=True)
+    skills = serializers.SerializerMethodField()
+    experiences = ExperienceSerializer(many=True, read_only=True)
+    educations = EducationSerializer(many=True, read_only=True)
+    emails = serializers.SerializerMethodField()
+    phone_numbers = serializers.SerializerMethodField()
+    pii_masked = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Profile
+        fields = (
+            "id", "external_id", "full_name", "first_name", "last_name", "gender", "headline",
+            "job_title", "job_title_role", "job_title_sub_role", "seniority_levels",
+            "current_company", "industry", "job_summary", "job_start_date",
+            "location_name", "location_locality", "location_region", "location_country",
+            "location_continent", "summary", "years_experience", "inferred_salary",
+            "connections", "interests", "languages", "linkedin_url", "linkedin_username",
+            "github_url", "twitter_url", "skills", "experiences", "educations",
+            "emails", "phone_numbers", "pii_masked",
+        )  # fmt: skip
+
+    def get_skills(self, obj: Profile) -> list[dict[str, Any]]:
+        return [
+            {"name": link.skill.name, "slug": link.skill.slug} for link in obj.profile_skills.all()
+        ]
+
+    def get_pii_masked(self, obj: Profile) -> bool:  # noqa: ARG002
+        return not self._can_view_pii()