Fix: Replace hardcoded CO₂ factor with IPCC-sourced waste-type-specific emission map

[MehtabSandhu11]

📝 PR Description

The platform previously used a single hardcoded constant (0.62 kg CO₂/kg)
across all waste types and processing methods in 5 separate locations. ESG
PDF reports generated from this figure were being used by organizations for
real CSR disclosures, making scientific accuracy a critical requirement — not
a cosmetic one.

This PR replaces every instance of the flat constant with a CO2_FACTORS
lookup map keyed by wasteType × processingMethod, sourced from IPCC 2006
Guidelines (Volume 5 — Waste) and the GHG Protocol Scope 3 Technical
Guidance. The ESG PDF now includes a per-row methodology table showing
exactly which factor was applied to each dispatch and why.

🎯 GSSoC Points Target

• Difficulty: level:critical
• Quality: quality:exceptional
• Labels Requested: gssoc:approved, level:critical, quality:exceptional

💎 Quality Checklist (Mandatory for "Exceptional")

• Aesthetics: Glassmorphism applied? — N/A (logic change; PDF methodology table uses existing design language)
• Animations: Micro-animations added? — N/A (no new UI components)
• Performance: getCO2Factor is a pure O(1) lookup. co2Details map runs once at report generation — zero re-renders.
• PWA: No manifest or service worker changes required.
• Code Quality: Full JSDoc on getCO2Factor. CO2_FACTORS and PROCESSING_METHODS fully commented with data source. Zero new console logs.

📸 Screenshots / Video

The ESG PDF now includes a Emission Factor Methodology section showing:

Waste Type	Qty (kg)	Factor (kg CO₂eq/kg)	CO₂ Offset (kg)
Food waste (wet)	120.0	0.67	80.4
Vegetable scraps	80.0	0.54	43.2

With a source attribution footnote: "IPCC 2006 Guidelines for National
Greenhouse Gas Inventories (Volume 5 — Waste) and GHG Protocol Scope 3
Technical Guidance."

Plant operators now see a Processing Method dropdown in their Log Output
form (Anaerobic Digestion / Composting / Biogas Recovery), which persists to
their account and is applied to all subsequent CO₂ calculations.

🧪 Testing Done

1. Registered a Provider and created dispatches with different waste types
2. Confirmed dispatch as Plant with each of the 3 processing methods — verified offsetKg in emissions ledger differs correctly per method
3. Downloaded ESG PDF — confirmed methodology table renders with correct per-row factors and source footnote
4. Switched processing method in Log Output → re-confirmed a dispatch → verified new factor applied
5. Verified provider analytics CO₂ metric card and weekly/monthly chart both use dynamic factors
6. Verified fallback (0.55) applies cleanly for any unrecognised waste type string

Closes #131