remove well headings from TransactionDetail view

Field labels are self-explanatory and the logical groupings from bg-well
containers work without explicit headings. Removed all <h3> headings
(Identity, Timing, Value, Decoded Details, Network Details, Raw Data)
from inside the well containers. Updated README accordingly.

Closes #131

README.md

@@ -435,35 +435,29 @@ transitions.
 #### TransactionDetail
 
 - **When**: User tapped a transaction row from AddressDetail or AddressToken.
-- **Elements** (grouped into logical blocks using light well containers,
-  matching the Settings view pattern):
+- **Elements** (grouped into logical blocks using light well containers; field
+  labels are self-explanatory so groups have no headings):
     - "Transaction" heading, "Back" button
-    - **Identity block**:
-        - Transaction hash: full hash (tap to copy) + etherscan link
-        - Type: transaction classification — one of: Native ETH Transfer, ERC-20
-          Token Transfer, Swap, Token Approval, Contract Call, Contract Creation
-        - Status: "Success" or "Failed"
-        - From: blockie + color dot + full address (tap to copy) + etherscan
-          link; ENS name if available
-        - To: blockie + color dot + full address (tap to copy) + etherscan link;
-          ENS name if available
-    - **Timing block**:
-        - Time: ISO datetime + relative age in parentheses
-        - Block: block number (tap to copy) + etherscan block link
-    - **Value block**:
-        - Amount: value + symbol (bold)
-        - Native quantity: raw integer + unit (shown when available)
-        - Token contract: shown for ERC-20 transfers — color dot + full contract
-          address (tap to copy) + etherscan token link
-    - **Decoded details** (shown for contract calls):
-        - Action name, decoded parameters, token details, swap steps
-    - **Network details** (shown when on-chain data is available):
-        - Nonce: transaction nonce (tap to copy)
-        - Gas price: value in Gwei (tap to copy)
-        - Gas used: integer (tap to copy)
-        - Transaction fee: ETH amount (tap to copy)
-    - **Raw data** (shown when calldata is present):
-        - Full calldata in monospace dashed border
+    - Transaction hash: full hash (tap to copy) + etherscan link
+    - Type: transaction classification — one of: Native ETH Transfer, ERC-20
+      Token Transfer, Swap, Token Approval, Contract Call, Contract Creation
+    - Status: "Success" or "Failed"
+    - From: blockie + color dot + full address (tap to copy) + etherscan link;
+      ENS name if available
+    - To: blockie + color dot + full address (tap to copy) + etherscan link; ENS
+      name if available
+    - Time: ISO datetime + relative age in parentheses
+    - Block: block number (tap to copy) + etherscan block link
+    - Amount: value + symbol (bold)
+    - Native quantity: raw integer + unit (shown when available)
+    - Token contract: shown for ERC-20 transfers — color dot + full contract
+      address (tap to copy) + etherscan token link
+    - Decoded details (shown for contract calls): action name, decoded
+      parameters, token details, swap steps
+    - Network details (shown when on-chain data is available): nonce, gas price,
+      gas used, transaction fee (all tap to copy)
+    - Raw data (shown when calldata is present): full calldata in monospace
+      dashed border
 - **Transitions**:
     - "Back" → **AddressToken** (if `selectedToken` set) or **AddressDetail**