feat: Add floating sidebar navigation and dark theme support

- Add floating pill-shaped sidebar with navigation icons
- Implement dark/light theme toggle with localStorage persistence
- Update all figure factories for transparent backgrounds
- Use carto-darkmatter map style for choropleths
- Add methodology link button to Toronto dashboard header
- Add back to dashboard button on methodology page
- Remove social links from home page (now in sidebar)
- Update CLAUDE.md to Sprint 7

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

portfolio_app/pages/home.py

@@ -2,7 +2,6 @@
 
 import dash
 import dash_mantine_components as dmc
-from dash_iconify import DashIconify
 
 dash.register_page(__name__, path="/", name="Home")
 
@@ -52,19 +51,6 @@ PROJECTS = [
     },
 ]
 
-SOCIAL_LINKS = [
-    {
-        "platform": "LinkedIn",
-        "url": "https://linkedin.com/in/leobmiranda",
-        "icon": "mdi:linkedin",
-    },
-    {
-        "platform": "GitHub",
-        "url": "https://github.com/leomiranda",
-        "icon": "mdi:github",
-    },
-]
-
 AVAILABILITY = "Open to Senior Data Analyst, Analytics Engineer, and BI Developer opportunities in Toronto or remote."
 
 
@@ -160,27 +146,6 @@ def create_projects_section() -> dmc.Paper:
     )
 
 
-def create_social_links() -> dmc.Group:
-    """Create social media links."""
-    return dmc.Group(
-        [
-            dmc.Anchor(
-                dmc.Button(
-                    link["platform"],
-                    leftSection=DashIconify(icon=link["icon"], width=20),
-                    variant="outline",
-                    size="md",
-                ),
-                href=link["url"],
-                target="_blank",
-            )
-            for link in SOCIAL_LINKS
-        ],
-        justify="center",
-        gap="md",
-    )
-
-
 def create_availability_section() -> dmc.Text:
     """Create the availability statement."""
     return dmc.Text(AVAILABILITY, size="sm", c="dimmed", ta="center", fs="italic")
@@ -193,7 +158,6 @@ layout = dmc.Container(
             create_summary_section(),
             create_tech_stack_section(),
             create_projects_section(),
-            create_social_links(),
             dmc.Divider(my="lg"),
             create_availability_section(),
             dmc.Space(h=40),

portfolio_app/pages/toronto/dashboard.py

@@ -3,6 +3,7 @@
 import dash
 import dash_mantine_components as dmc
 from dash import dcc, html
+from dash_iconify import DashIconify
 
 from portfolio_app.components import (
     create_map_controls,
@@ -76,6 +77,17 @@ def create_header() -> dmc.Group:
             ),
             dmc.Group(
                 [
+                    dcc.Link(
+                        dmc.Button(
+                            "Methodology",
+                            leftSection=DashIconify(
+                                icon="tabler:info-circle", width=18
+                            ),
+                            variant="subtle",
+                            color="gray",
+                        ),
+                        href="/toronto/methodology",
+                    ),
                     create_year_selector(
                         id_prefix="toronto",
                         min_year=2020,

portfolio_app/pages/toronto/methodology.py

@@ -2,7 +2,8 @@
 
 import dash
 import dash_mantine_components as dmc
-from dash import html
+from dash import dcc, html
+from dash_iconify import DashIconify
 
 dash.register_page(
     __name__,
@@ -18,8 +19,18 @@ def layout() -> dmc.Container:
         size="md",
         py="xl",
         children=[
+            # Back to Dashboard button
+            dcc.Link(
+                dmc.Button(
+                    "Back to Dashboard",
+                    leftSection=DashIconify(icon="tabler:arrow-left", width=18),
+                    variant="subtle",
+                    color="gray",
+                ),
+                href="/toronto",
+            ),
             # Header
-            dmc.Title("Methodology", order=1, mb="lg"),
+            dmc.Title("Methodology", order=1, mb="lg", mt="md"),
             dmc.Text(
                 "This page documents the data sources, processing methodology, "
                 "and known limitations of the Toronto Housing Dashboard.",