fix: alpha-as-TAO unit mixup for stakes

[kkowalski-reef]

Fix α-as-τ unit confusion in stake handling

Stake was typed as Balance (τ) when it's α. The CLI showed α and τ columns with identical numbers, printed α with a τ label, and summed α across subnets - meaningless, since α is only comparable within a subnet at its price.

• Retypes stake as AlphaBalance across neuron / metagraph / stake / delegate data, fetches per-subnet prices to convert α→τ, and shows α alongside a priced τ-equivalent (- when the price RPC is unavailable).
• Cross-subnet totals convert to τ before summing.
• JSON/CSV stake fields now carry α plus a separate τ-equivalent and price; τ-equiv totals are null when prices can't be fetched.

[kkowalski-reef]

Some examples:

$ agcli diff portfolio --address 5FRXwb2qsEhqDQQKcm5m2MF26xTWwW65MHTEtKFFydypuqjG --block1 8515147 --block2 8515362

===== BEFORE =====
================================
Portfolio Diff: 5FRXwb2qsEhqDQQKcm5m2MF26xTWwW65MHTEtKFFydypuqjG (block 8515147 → 8515362)

                         Block 8515147   Block 8515362          Change
      Free balance (τ)          6.8367          6.8367               0
       Total stake (τ)     345450.3459     345490.3754        +40.0295
             Total (τ)     345457.1827     345497.2121        +40.0295
       Stake positions              11              11

===== AFTER =====
Portfolio Diff: 5FRXwb2qsEhqDQQKcm5m2MF26xTWwW65MHTEtKFFydypuqjG (block 8515147 → 8515362)

                         Block 8515147   Block 8515362          Change
      Free balance (τ)          6.8367          6.8367               0
         Total stake τ       4378.3131       4379.8393         +1.5261
             Total (τ)       4385.1499       4386.6760         +1.5261
       Stake positions              11              11

---

$ agcli view neuron --netuid 1 --uid 252

===== BEFORE =====
================================
Neuron UID 252 on SN1
  Hotkey:          5HbNZ77cXQXbUjXG3YLVBGk6N4WbtKtGQYAWLXd2aWa8fqGe
  Coldkey:         5FRXwb2qsEhqDQQKcm5m2MF26xTWwW65MHTEtKFFydypuqjG
  Active:          true
  Stake:           392527.115480885 τ
  Rank:            0.000000
  Trust:           0.000000
  Consensus:       0.000000
  Incentive:       0.000000
  Dividends:       0.610010
  Emission:        24.7609 τ
  Val. Trust:      0.999985
  Val. Permit:     true
  Pruning Score:   1.000000
  Last Update:     8515324
  Axon:            :::0 (v0, proto 0)
  Prometheus:      :::0 (v0)

===== AFTER =====
Neuron UID 252 on SN1
  Hotkey:          5HbNZ77cXQXbUjXG3YLVBGk6N4WbtKtGQYAWLXd2aWa8fqGe
  Coldkey:         5FRXwb2qsEhqDQQKcm5m2MF26xTWwW65MHTEtKFFydypuqjG
  Active:          true
  Stake:           392527.115480885 α ≈ 3426.797830643 τ
  Rank:            0.000000
  Trust:           0.000000
  Consensus:       0.000000
  Incentive:       0.000000
  Dividends:       0.610010
  Emission:        24.7609 α/tempo ≈ 0.2162 τ
  Val. Trust:      0.999985
  Val. Permit:     true
  Pruning Score:   1.000000
  Last Update:     8515324
  Axon:            :::0 (v0, proto 0)
  Prometheus:      :::0 (v0)

---

$ agcli view validators --netuid 1 --limit 8

===== BEFORE =====
================================
Validators on SN1 (8 with permits)
+-----+-------------+--------------+--------+-----------+-----------+
| UID | Hotkey      | Stake        | VTrust | Dividends | Emission  |
+===================================================================+
| 252 | 5HbN...fqGe | 392527.1155τ | 1.0000 | 0.6100    | 24.7609 τ |
|-----+-------------+--------------+--------+-----------+-----------|
| 138 | 5E2L...eZ5u | 153671.3127τ | 0.9998 | 0.0031    | 0.1271 τ  |
|-----+-------------+--------------+--------+-----------+-----------|
| 52  | 5D1s...KGs1 | 113464.4486τ | 1.0000 | 0.0617    | 2.5054 τ  |
|-----+-------------+--------------+--------+-----------+-----------|
| 226 | 5Hmk...25H7 | 56018.5259τ  | 0.9999 | 0.0488    | 1.9812 τ  |
|-----+-------------+--------------+--------+-----------+-----------|
| 26  | 5Ev5...nh9s | 13955.0851τ  | 0.8919 | 0.0543    | 2.2027 τ  |
|-----+-------------+--------------+--------+-----------+-----------|
| 251 | 5H6y...TVRf | 11684.4877τ  | 1.0000 | 0.1031    | 4.1844 τ  |
|-----+-------------+--------------+--------+-----------+-----------|
| 248 | 5HCF...gDHh | 9629.0079τ   | 0.0000 | 0.0000    | 36.4398 τ |
|-----+-------------+--------------+--------+-----------+-----------|
| 253 | 5CUb...2XSG | 5287.3357τ   | 1.0000 | 0.1037    | 4.2091 τ  |
+-----+-------------+--------------+--------+-----------+-----------+

===== AFTER =====
Validators on SN1 (8 with permits)
+-----+-------------+---------------+------------------+--------+-----------+--------------+
| UID | Hotkey      | Stake (α)     | ≈ τ              | VTrust | Dividends | Emission (α) |
+==========================================================================================+
| 252 | 5HbN...fqGe | 392527.1155 α | 3426.797830643 τ | 1.0000 | 0.6100    | 24.7609 α    |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 138 | 5E2L...eZ5u | 153671.3127 α | 1341.564697917 τ | 0.9998 | 0.0031    | 0.1271 α     |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 52  | 5D1s...KGs1 | 113464.4486 α | 990.555075000 τ  | 1.0000 | 0.0617    | 2.5054 α     |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 226 | 5Hmk...25H7 | 56018.5259 α  | 489.046885219 τ  | 0.9999 | 0.0488    | 1.9812 α     |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 26  | 5Ev5...nh9s | 13955.0851 α  | 121.829176828 τ  | 0.8919 | 0.0543    | 2.2027 α     |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 251 | 5H6y...TVRf | 11684.4877 α  | 102.006652166 τ  | 1.0000 | 0.1031    | 4.1844 α     |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 248 | 5HCF...gDHh | 9629.0079 α   | 84.062124550 τ   | 0.0000 | 0.0000    | 36.4398 α    |
|-----+-------------+---------------+------------------+--------+-----------+--------------|
| 253 | 5CUb...2XSG | 5287.3357 α   | 46.158926740 τ   | 1.0000 | 0.1037    | 4.2091 α     |
+-----+-------------+---------------+------------------+--------+-----------+--------------+